ANNUAL  REPORT 

— OF  — 

Field  Work  and  Analyses. 


GEOLOGY  OF 

COLORADO  COAL  DEPOSITS. 

— BY  — 


PROF.  iLRTHTJR  Hi  FL.  TP  ES, 


DENVER,  COLO.: 

NEWS  PRINTING  COMPANY. 
1889. 


State  School  of  Mines 


OF  COLORADO. 


TRUSTEES. 


Fred.  Steinhauer,  President , Denver,  Arapahoe  Co. 
Jas.  T.  Smith,  Secretary , Denver,  Arapahoe  Co. 

A.  A.  Beow,  Leadville,  Lake  Co. 

Ed.  F.  Browne,  Aspen,  Pitkin  Co. 

J.  Perry  Keeey,  Golden,  Jefferson  Co. 


MORITZ  BARTH,  Treasurer, 

Denver,  Arapahoe  Co. 


FACULTY. 


REGIS  CHAUVENET,  A.  M.,  B.  S,  President, 
Professor  of  Chemistry. 

ARTHUR  LAKES, 

Professor  of  Geology  and  Drawing , 
Curator  of  the  Museum. 

MAGNUS  C.  IHLSENG,  E.  M.,  C.  E.,  Ph.  D., 
Professor  of  Engineering . 

PAUL  MEYER,  Ph.  D., 

Professor  of  Mathematics. 

BENJ.  SADTLER,  A.  M.,  B.  S., 

Professor  of  Metallurgy  and  Mineralogy. 

GEORGE  C.  TILDEN,  C.  E., 

Laboratory  Instructor. 


Colorado  State  School  of  Mines. 


State  School  of  Mines,  \ 
Golden,  Oct.  31,  1889.  / 


Dr.  F.  Steinhauer, 

President  of  Board  of  Trustees : 

Dear  Sir  : — I transmit  herewith  the  report,  by  Professor 
Arthur  Lakes,  on  the  Geology  of  Colorado  Coal  Deposits,  which 
forms  the  report  for  the  year  1889  of  the  State  School  of  Mines. 

> 


Respectfully  yours, 


REGIS  CHAUVENET, 

President  of  Faculty. 


> 


/ 


55''3.a4-G97fefc' 

u»i 


PREFACE. 


This  work  is  a sequel  to  that  on  the  “ Geology  of  Colorado 
ore  deposits”  published  a year  ago  by  the  writer,  under  the 
auspices  of  the  School  of  Mines.  It  is  written  somewhat  in  the 
same  strain,  with  a view  to  meeting  the  needs  of  the  general 
public,  and  the  ordinary  coal  miner. 

A great  deal  has  been  published  already  in  past  years  by  the 
official  Government  Geological  Surveys,  and  by  other  parties,  on 
the  coal  fields  of  Colorado,  but  the  rapid  development  of  the 
State,  especially  of  late,  by  the  incoming  of  new  or  extended 
railroad  lines,  has  opened  up  so  many  new  coal  districts,  as  well 
as  greatly  enlarged  the  number  of  mines  and  developments  in 
older  fields,  that  there  is  ample  scope  for  many  fresh  reports. 
The  field,  too,  is  a very  large  one  and  exceedingly  varied, 
both  in  its  geological  and  economical  characters.  The  coal 
fields  are  often  situated  in  very  picturesque  regions,  some 
of  them  being-  singularly  interesting  in  geological  character. 
While  we  have  made  these  fields,  their  practical,  econom- 
ical and  geological  features,  the  leading  topic  of  this  work, 
we  have  digressed  occasionally  to  call  attention  to  some 
striking  geological  phenomena  in  the  vicinity  of  the  coal, 
though  not  directly  connected  with  it,  so  that  the  traveler  or  coal 
miner  may,  if  he  wishes,  form  some  idea  of  the  structure  of  the 
country  passed  through  on  his  way  to  the  coal  mines,  or  of  what 
is  to  be  seen  of  special  interest  within  easy  reach  of  the  mining 
camp. 

The  illustrations  accompanying  this  work  were  engraved  by 
the  American  Bank  Note  Company  of  New  York,  from  sketches 
made  in  the  field  by  the  writer.  They  will  give  an  idea  of  the 
general  appearance  of  the  coal  .fields,  and  of  the  location  of  the 
mines,  while  the  geological  sections  accompanying  the  surface 
sketches  will  show  the  number,  thickness  and  relation  of  the  dif- 
ferent coal  seams  as  revealed  by  underground  workings,  or  by 


natural  outcrops.  The  general  sections  of  the  surrounding' 
region  show  where  the  cpal  comes  in  among  the  various  groups 
of  strata  successively  revealed  by  upheaval  along  the  flanks  of 
our  mountain  ranges. 

As  regards  unavoidable  scientific  terms,  such  as  names  of 
geological  periods,  etc.,  we  may  refer  the  reader  to  the  intro- 
duction to  our  work  on  the  “ Geology  of  Colorado  Ore 
Deposits,”  where  a brief  explanation  is  given  of  some  of  these 
terms,  or  else  to  some  elementary  work  on  geology,  such  as 
those  of  Professors  Shaler,  Dana,  or  Le  Conte. 

The  first  chapter  is  devoted  to  the  not  unfrequently  asked 
question,  “ What  is  coal?”  We  have  endeavored  to  give  a brief 
sketch  of  its  natural  history,  and  to  point  out  some  of  its  char- 
acteristics and  modes  of  occurrence  in  Colorado,  as  a preliminary 
to  the  more  detailed  accounts  in  succeeding  chapters. 

To  describe  minutely  and  accurately  all  the  coal  fields  of 
Colorado  would  demand  much  greater  space  than  that  allotted  to 
this  work.  We  have  confined  ourselves  to  such  districts  as  are 
actually  being  developed,  and  are  situated  along,  or  within  easy 
distance  of  the  lines  of  railroad,  for  a coal  mine  without  a rail- 
road near  it  is  only  of  prospective  value.  There  are  large  areas 
of  very  valuable  coal  outside  of  the  railroad  limits,  which  we  did 
not  visit  this  year,  such  as  those  lying  along  the  Grand  River 
between  New  Castle  and  Grand  Junction,  the  White  River  Dis- 
trict, the  Middle  and  North  Park  Districts;  also,  a great  deal  of 
the  Gunnison  District,  down  Anthracite  Creek,  where  extensive 
coal  and  anthracite  deposits  are  known  to  exist;  also,  part  ot 
Southwestern  Colorado,  along  the  Montezuma  valley,  and  a great 
area  now  covered  by  the  Ute  reservation.  All  these  districts  are 
at  present  outside  of  railroad  limits,  and  come  under  the  class  of 
undeveloped  coal  fields  of  the  future,  which  may  form  the  sub- 
ject of  a future  report,  though,  with  the  rapid  strides  that  rail- 
roads are  making,  it  seems  likely  that  many  of  these  will  soon 
be  enrolled  under  the  class  of  developed  and  producing  fields. 
We  have  given  but  a passing  notice  to  old  and  well  established 
mines,  (about  some  of  which  we  have  written  in  former  reports) 
concentrating  our  attention  mainly  on  young  and  new  mines, 
or  those  in  newly  opened  districts,  which  will  show  the  public 


the  rapid  progress  being  made  in  our  coal  mining  industry,  and 
the  great  extent  and  value  of  our  available  coal  fields.  We  have 
taken  some  pains  to  call  attention  not  only  to  their  great 
resources,  but  also  to  the  excellent  quality  of  our  coal,  points 
which  we  think  have  not  been  sufficiently  recognized  in  the  past, 
since,  while  people  generally  recognize  Colorado  as  a leading 
precious  metal  producer,  they  are  slow  to  admit  it  as  a leading 
coal  producing  state  also. 

In  the  appendix  at  the  end  of  this  work  is  an  epitome  of  the 
statistical  report  of  the  State  Inspector  of  coal  mines,  Hon.  John 
McNeil,  to  whose  valuable  publications  we  refer  the  reader  for 
matters  of  a statistical  character. 

The  analyses  accompanying  this  work  were  chiefly  made  by 
Prof.  Geo.  C.  Tilden,  of  the  School  of  Mines,  who  accompanied 
the  writer  on  some  of  his  trips,  taking  the  samples  personally. 
Messrs,  van  Dyke,  Thies,  Johnson,  Camp,  and  Wertheim,  students 
of  the  school,  accompanied  us  at  different  times,  and  rendered 
valuable  assistance.  Our  thanks  are  due  to  the  superintendents 
of  the  various  coal  mines,  who  gave  us  all  possible  help  in  our 
examinations,  and  also  to  the  Rio  Grande  and  Midland  Railways, 
for  assistance  over  their  lines,  recognizing,  as  they  must,  that  this 
work  is  for  no  private  interest,  but  for  the  benefit  of  Colorado 
generally,  perhaps  especially  for  that  of  th$  railroad  companies. 

State  School  of  Mines, 

Golden,  August,  1889. 


Digitized  by  the  Internet  Archive 
in  2017  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/geologyofcolorad00lake_0 


CHAPTER  I. 


Natural  History  of  Coal. 


Chapter  I 

NATURAL  HISTORY  OF  COAL. 

“What  is  coal?”  is  a question  that  doubtless  has  often 
occurred  to  the  thoughtful  miner,  who  has  worked  perhaps 
all  his  life  in  coal  mines,  in  England,  Pennsylvania  or  Colorado, 
and  is  practically  familiar  with  the  substance  in  nearly  all  its 
known  forms  and  with  nearly  every  condition  under  which  it  is 
found.  The  same  question  may  also  have  entered  the  mind  of 
the  housewife,  who  is  familiar  with  the  stove  or  coal-bin,  and 
recognizes  that  for  household  purposes  some  coal  is  much  better 
than  others. 

Occasionally  the  miner  comes  across  a hard  round  cylinder 
of  coal  or  “ bone  ” in  his  mine  which  suggests  a resemblance  to 
the  trunk  of  a tree,  and  if  an  observing  man,  in  first  opening  the 
seam,  he  will  frequently  have  noticed  in  the  shale  and  sandstone 
above  it,  impressions  of  leaves,  and  in  Colorado  even  of  palm 
leaves  and  ferns,  and  in  the  underclay  beneath  every  seam  a 
great  number  of  what  look  like  rootlets.  Perhaps  his  suspicion 
that  the  cylinder  was  once  a tree-trunk  may  be  confirmed  by 
finding  that  it  passes  down  through  the  coal  seam  and  actually 
sends  off  roots  into  the  underclay,  the  idea  thus  dawning  upon 
him  that  somehow  coal  is  connected  with  ancient  relics  of  vege- 
tation. Forests  and  plants  have  lived  and  died  for  ages  upon 
this  world ; what  became  of  the  dead  forests  ? Perhaps  here  in 
this  coal  seam  are  some  of  their  remains  in  a different  form, 
sealed  under  tons  of  rock.  The  underclay  was  the  soil  upon 
which  the  trees  grew ; the  coal  seam  is  the  leaf  mould,  dead 
branches  and  trunks,  accumulated  for  ages  around  the  stumps, 
covered  up  by  sand  and  pebbles,  till  by  pressure,  moisture,  heat 
and  chemical  action  they  are  reduced  to  the  hard  mineral  sub- 
stance called  coal. 

Not  far  from  the  coal  mine  is  a swamp  which  they  are  trying 
to  drain  by  cutting  a deep  trench.  The  surface  of  the  marsh  is 


14 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


covered  with  thick  moss  and  sedges,  and  yields  as  we  walk  over 
it,  like  an  india-rubber  sheet.  In  places  towards  the  center  of 
the  marsh  is  a pond  of  clear  water,  and  it  is  evident  that  the 
whole  swamp  is  underlaid  by  a stratum  of  water  or  ooze.  Where 
they  are  cutting  the  trench  we  see  the  moss,  green  and  living,  on 
top  of  a dead  fibrous  mass  of  the  same  material,  and  below  that 
an  impalpable  black  mud,  evidently  composed  of  the  same,  only 
older  material,  reduced  by  water  and  pressure  to  a black 
vegetable  pulp  called  peat.  This  rests  upon  a thin  layer  of  clay, 
and  that  again  upon  a bed  of  pebbles,  sand  or  even  hard  rock. 
The  marsh  is  deepest  towards  the  center,  like  a basin,  and  thins 
out  along  the  edges  ; the  peat  also  is  thickest  towards  the  center. 
Scattered  over  the  marsh,  imbedded  in  the  moss  and  mud,  are 
trunks  and  stools  of  trees  which  once  grew  there,  till  they  rotted 
and  fell,  and  in  the  section  shown  by  the  ditch  their  roots  may 
be  seen  running  down  into  the  clay  seam.  Dead  leaves  and 
branches  are  also  found  mixed  up  in  the  peat,  which  are  turning 
black  and  passing  into  that  substance.  A freshet  from  the  hills, 
like  one  of  our  Colorado  cloudbursts,  has  lately  rushed  down 
into  the  swamp  and  covered  quite  a large  part  of  it  with  a layer 
of  sand  and  pebbles,  mingled  with  tree-trunks.  The  winds,  too, 
keep  blowing  the  autumnal  leaves  from  the  surrounding  forest 
into  the  swamp.  Occasionally  we  come  upon  the  bones  of  some 
animal,  a cow  or  deer,  which  was  mired,  or  whose  carcass  was 
carried  in  by  the  freshet ; for  a marsh  is  a general  dumping- 
place  of  all  the  rubbish  brought  down  from  the  higher  country. 
The  marsh  throws  light  on  our  coal  seams  The  peat  which 
burns  dull  when  dried  is  very  like  some  of  our  poorest  class 
of  coal  called  “brown  lignite;”  and  if  these  freshets  keep  on 
at  intervals  for  many  years  and  cover  up  the  old  swamp  with 
a great  thickness  of  sand  and  pebbles,  the  peat  will  turn  into 
brown  lignite.  If  the  accumulation  goes  on  to  such  a degree 
that  a thickness  of  some  hundreds  of  feet  is  formed,  the  pressure 
being  assisted  by  chemical  action  and  a certain  amount  of  heat,* 
the  coal  will  become  more  compact  and  turn  into  bituminous  or 
ordinary  coal. 

* Increasing  under  great  thickness  of  rock  at  the  rate  of  one  degree  for  every  fifty 
feet,  as  many  a miner  who  has  worked  in  very  deep  collieries  knows. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


15 


Now  should  some  convulsion  of  nature  occur,  and  all  the 
strata  with  their  included  coal  seam  be  crumpled  up  into  a 
mountain  mass,  the  heat  produced  by  this  movement,  together 
with  that  from  lava  or  porphyry,  which  often  issues  in  connec- 
tion with  such  movements,  might  further  change  the  coal  into 
that  hard  substance  called  “anthracite”  by  a slow  stewing  pro- 
cess, by  which  certain  volatile  elements  of  the  common  coal 
would  be  driven  out,  leaving  almost  pure  carbon  behind.  Some- 
times, if  the  heat  is  very  great,  such  as  that  caused  by  the 
intrusion  of  a lava  dyke,  the  anthracite  is  further  changed  into 
the  substance  called  “graphite”  or  “plumbago,”  which  we  use 
for  lead  pencils,  and  which,  singularly  enough,  though  a pure 
carbon,  produced  by  the  action  of  heat  itself,  burns  only  with 
difficulty,  but  is  better  than  fire-brick  for  resisting  heat. 

The  miner  in  Colorado  will  recall  mines  in  his  experience, 
such  as  in  the  Trinidad  region,  where  coal  has  been  thus 
changed  to  a hard  natural  coke,  or  to  graphite,  by  a dyke  of  lava 
crossing  the  seam ; the  dyke  he  will  remember  to  his  cost,  from 
its  extreme  hardness.  If  he  has  worked  about  Crested  Butte,  he 
will  have  noticed  how  near  the  great  dykes  and  mountains  of 
porphyry  came  to  the  coal  seams,  and  how  the  coal  is  there  in 
some  localities  anthracite,  as  also  on  Rock  Creek  in  the  same 
region,  where  huge  masses  of  strata  are  overturned,  folded  and 
crumpled  up  like  sheets  of  paper,  while  in  the  more  level  portion 
of  the  Gunnison  district  the  coal  is  only  common  bituminous. 
On  reflection,  he  will  also  see  that  the  coking  coal  area,  as  at 
Trinidad  or  Crested  Butte,  is  always  within  a moderate  distance 
of  some  lava-capped  or  volcanic  mountains,  or  where  moderate 
overturning  and  uptilting  have  taken  place,  and  he  concludes 
with  reason  that  many  of  the  varieties  of  coal,  such  as  coking 
coal  or  anthracite,  are  due  to  nothing  peculiar  in  the  coal  itself, 
but  to  the  influence  of  these  volcanic  agencies  and  to  greater  or 
less  heat  or  pressure. 

So  much  for  a single  coal  seam,  but  the  miner  often  finds 
three  or  four  or  even  a dozen  seams  of  varying  thickness,  one 
above  another,  separated  by  belts  of  sandstone  and  shale,  with 
the  same  phenomena  repeated  in  each.  Now  supposing  that  the 
sand  brought  in  by  the  freshet  upon  our  marsh,  were  again 


1 6 GEOLOGY  OF  COLORADO  COAL  FIELDS. 

covered  by  vegetation,  and  again  became  a marsh,  and  was  cov- 
ered likewise  by  freshet  sand,  we  should  then  have  two  coal 
seams,  and  if  this  process  were  repeated  again  and  again,  a great 
number  of  seams  would  be  so  formed,  but  it  is  obvious  that  in 
time  we  should  completely  fill  up  the  natural  depression  or  basin 
of  the  marsh,  and  it  would  form  dry  land,  in  which  coal  could 
not  form  well  for  lack  of  moisture.  It  has  been  found  that  areas 
where  great  thickness  of  sediments  are  being  laid  down,  grad- 
ually sink,  which  sinking,  if  kept  up,  will  allow  any  number  of 
different  beds,  and  any  amount  of  thickness  to  accumulate,  and 
yet  keep  the  surface  of  the  marsh  or  lake  near  water  level,  or  in 
shallow  water.  Thus  large  deltas,  like  those  of  the  Mississippi 
and  of  the  Nile,  are  found  to  be  gradually  sinking,  and  borings 
in  them  show  that  this  has  been  in  progress  for  an  enormous 
length  of  time,  as  one  forest  bed  after  another  has  been  found, 
separated  by  intervals  of  sandstone,  just  as  in  our  coal  beds. 
Gradual  sinking  and  elevation  of  land  are  found  by  careful  meas- 
urements to  be  going  on  all  the  world  over,  especially  along  the 
coasts  of  our  continents,  where  the  greatest  amount  of  sediment 
is  being  accumulated  in  the  sea,  washed  down  from  the  land  by 
rivers. 

The  writer  saw  in  the  bay  of  Torquay  in  Devonshire,  (England) , 
a peat-bed  uncovered  at  low  tide,  which  extends  from  the  neigh- 
boring marshes  and  dry  land  down  under  the  sands,  below  the 
deep  waters  of  the  bay.  On  land  the  green  mossy  turf  is  growing, 
but  when  traced  down  to  the  shore  it  becomes  a black  peat-mud, 
covered  by  the  shells  and  sands  of  the  beach,  and  finally  lost 
beneath  the  waves.  On  the  coast  of  Guernsey  also,  at  a very 
low  tide,  may  be  seen  a peat  forest  exposed  on  the  beach  and 
dug  up  for  fuel,  acorns  and  fragments  of  oak  branches  being 
easily  distinguished  in  the  blackened  peat.  As  these  trees  and 
mosses  once  grew  on  land,  it  is  evident  that  the  area  must  have 
subsided.  Now  in  these  two  cases  of  subsidence,  if  the  buried 
areas  were  again  uplifted  into  land,  the  sands  having  consolidated 
into  sandstone,  and  the  peat  into  coal,  we  should  find  the  sand- 
stone, overlying  the  beds  of  coal,  full  of  fossil  sea  shells,  as  are 
the  rocks  in  some  cases,  above  the  coal  beds  of  Pennsylvania,  but 
if  the  same  process  were  carried  on,  in  the  bed  of  a great  inland 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


1 7 


lake  or  marsh,  we  should  find  sandstone,  with  occas/onal  traces 
of  land  vegetation,  and  a few  fresh  water  shells  overlying  the 
coal,  as  in  some  cases  in  Colorado.  If,  however,  the  marsh,  as 
is  often  the  case,  were  along  the  sea  coast,  as  a delta,  or  bordering 
swamp-land,  as  in  Florida,  we  might  expect  to  find  some  evi- 
dences of  salt-water  mixed  with  the  fresh,  and  brackish  shells 
abounding.  Such  is  in  fact  the  case  in  a few  instances  in  Colo- 
rado, as  in  the  Newcastle,  Durango  and  Marshall  mines. 

Sometimes  the  prospector,  after  following  a coal  seam  of  a 
certain  thickness  for  many  miles,  finds  it  split  up  into  two  or  more 
beds  by  a thick  parting  of  shale  or  sandstone,  returning  to  its  orig- 
inal size  after  some  miles  more.  In  this  case,  as  at  Torquay,  we 
may  suppose  that  while  the  peat  was  forming,  one  part  of  the 
marsh  sank  much  more  than  the  other,  the  sunken  portion  would 
thus  be  covered  with  a thick  deposit  from  the  waters,  and  it  might 
be  a long  time  before  the  bed  of  the  lake  was  built  up  by  sedi- 
ment to  the  former  level  of  the  marsh,  and  continued  making 
peat  of  the  same  thickness  as  before.  The  small  thin  partings  of 
shale  so  commonly  found  in  coal  seams  may  result  from  subsi- 
dence, or  more  probably,  from  the  periodical  discharge  of  sand- 
laden streams  into  the  marsh,  while  the  peat  was  in  process  of 
formation.  It  is  also  not  uncommon  for  a number  of  seams, 
separated  by  comparatively  thick  partings,  to  unite  after  a certain 
distance  in  one  great  “mammoth”  seam,  as  at  Durango,  by  the 
gradually  thinning  out  of  the  partings ; they  are,  however,  gen- 
erally still  to  be  detected  in  a great  seam,  though  very  thin,  and 
for  this  reason  it  is  unusual  for  the  coal  in  a mammoth  seam  to  be 
as  pure  and  as  free  from  “ bone  ” or  slate  as  in  a small  individual 
seam.  Coal  seams  again  will  begin  small  and  gradually  thicken 
towards  a given  center,  from  which  they  will  again  begin  to  thin 
out,  as  in  the  case  of  our  peat-swamp,  and  for  the  reasons  already 
explained,  so  there  is  generally  a thick  portion  and  a thinner 
margin  around  our  coal  fields.  A vertical  or  uptilted  coal  seam, 
if  found  thin  near  the  surface,  is  not  likely  to  grow  rapidly 
thicker  within  the  depth  of  the  few  hundred  feet  to  which  a 
shaft  can  go,  a consideration  of  which  fact  would  prevent  a good 
deal  of  useless  prospecting  on  thinly  outcropping  seams.  Some 
local  compression  or  faulting  near  the  surface,  however,  may  have 


i8  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

pinched  the  seam  to  a minimum  thickness,  as  in  the  case  of  one 
of  the  Marion  mines,  while  further  in,  the  seam  may  widen  to 
its  true  dimensions.  Among  the  disturbed  and  faulted  strata,  such 
pinches  and  “ rolls  ” are  found  in  almost  every  mine,  and  were 
caused,  not  so  much  by  irregularities  in  the  original  deposition 
of  the  peat  in  the  bed  of  the  marsh,  as  by  subsequent  movements 
of  the  strata.  It  is  rarely  safe,  however,  to  go  to  any  great  depth 
on  a seam  outcropping  thinly  on  the  surface  in  hope  of  its  grow- 
ing thicker;  we  have  seen  many  such  openings  made  on  the 
merest  traces  of  coal,  and  much  labor  lost. 

Considering  that  the  low  lying  marshes  are  subject  so  fre- 
quently to  inundations  from  streams  carrying  silt,  mud,  and 
gravel,  it  is  remarkable  to  find  the  coal  seams  with  comparatively 
so  little  admixture  of  shale  or  other  impurities,  still  more  so, 
when  we  find  an  enormous  seam  like  that  of  Newcastle,  45  feet 
thick,  with  but  trifling  clay  partings.  But  if  we  examine  some 
of  our  great  swamps,  like  those  of  Florida,  we  shall  find  that  the 
center  of  the  swamp  is  surrounded  by  thick  forests  and  under- 
growth, and  frequently  there  is  a lake  of  perfectly  clear  water  in 
the  middle,  into  which  no  sediment  or  sand  finds  its  way,  the 
bottom  being  wholly  formed  of  pure  peat  and  decaying  leaves. 
The  reason  of  this  is,  that  the  waters  of  the  river  at  their  freshets, 
in  passing  through  this  network  of  foliage,  leave  all  their  impur- 
ities attached  to  the  outer  circle  of  vegetation,  and  enter  the 
marsh  filtered  as  through  a sieve,  perfectly  clear.  In  such  places 
the  coal  might  be  both  thick  and  pure. 

Under  the  microscope,  coal  shows  a black,  hard,  shining  mass 
of  vegetable  substance,  and  no  matter  how  compact  or  even 
anthracitic  the  coal  may  appear  to  the  eye,  the  microscope  will 
generally  detect  vegetable  tissues  in  it,  and  the  peculiar  patterns 
of  wood-cells  found  in  the  cross  sections  of  trees  and  plants.  In 
the  case  of  peat  and  lignite,  the  woody-fibre  and  remains  of  plants, 
are  obvious,  even  to  the  eye.  Some  of  the  coals  of  England  show 
small  microscopic  discs  in  them,  which  are  considered  to  be  the 
germ  cases,  or  pollen,  of  gigantic  club-mosses,  which  must  have 
shed  it  like  snow,  since  thick  beds  of  coal  are  formed  almost 
entirely  of  these  embryonic  seeds.  Doubtless  microscopic  sec- 
tions of  our  Colorado  coals,  would  detect  the  remains  of  many  of 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


l9 


the  trees,  leaves  and  plants  which  we  find  fossilized  in  the  rocks 
adjacent  to  the  coal  seam.  Coal  breaks  in  two  ways,  one  in  a 
plane  parallel  to  its  lamination  or  bedding  plane,  the  other  at  right 
angles  to  it,  producing  what  is  called  “end  and  face”  structure. 
Between  the  laminoes,  the  microscope  detects  a sooty  substance 
called  mineral  charcoal,  made  of  stems  of  leaves,  that  perished  on 
the  ground,  by  exposure  to  the  air,  and  were  not  consolidated 
into  coal. 

Coal,  as  we  have  said,  ranges  through  peat,  which  burns 
slowly  and  without  flame;  brown  lignite,  which  carries  a larger 
per  cent  of  water,  and  only  a moderate  per  cent  of  fixed  carbon, 
and  burns  with  a little  more  flame ; bituminous  coal,  which  is 
soft,  melts  in  the  fire,  burns  with  a long  flime,  and  has  a higher 
per  cent  of  carbon ; anthracite  which  is  hard,  brittle  and  shining, 
burning  with  almost  no  flame,  being  nearly  pure  carbon,  finally 
reaching  the  form  of  graphite  which  is  practically  pure  carbon. 
Cannel-coal  is  a variety  of  bituminous  coal  and  appears  to  have 
been  formed  of  the  finest  impalpable  peat  mud,  at  the  bottom  of 
the  marsh,  burns  with  a bright  flame  like  a candle,  is  of  a dull 
lustre  and  capable  of  being  polished.  Litttle  if  any  of  this  variety 
is  yet  known  in  Colprado. 

The  vegetable  origin  of  coal  is  apparent  from  what  we  have 
said,  but  some  of  the  chemical  transformations  of  the  process 
need  explanation. 

Various  gases,  such  as  oxygen,  hydrogen,  and  carbon  dioxide 
are  elements  of  either  air  or  water.  The  leaves  of  plants  absorb 
carbon  from  the  carbon  dioxide  of  the  atmosphere,  and  let  the 
oxygen  go  free. 

The  soil  yields  them  water,  and  in  it  hydrogen,  they  absorb 
also  into  their  being  a small  amount  of  mineral  substances  derived 
from  the  soil,  such  as  potash,  soda,  lime,  etc.  When  plants  are 
burnt,  it  is  the  giving  back  to  the  air  of  the  carbon  they  derived 
from  it,  that  causes  the  flame  and  smoke.  The  ash  they  leave 
is  the  mineral  substance  they  derived  from  the  ground.  Part  of 
the  ash  that  we  obtain  on  analysis  from  coal,  is  so  derived,  but 
the  larger  part  of  it  is  from  foreign  impurities,  such  as  mud  and 
sand,  drifted  into  the  marsh  and  mixed  up  with  the  peat.  A 
coal  would  be  considered  quite  pure,  if  its  ash  were  only  that 
which  was  derived  from  the  plants  that  formed  it. 


20 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


Trees  and  vegetation  in  dying  and  rotting,  yield  up  their  car- 
bon to  the  air,  in  the  same  way  as  by  burning,  so  for  ages  the 
living  forest  has  been  above  ground,  its  roots  in  the  subsoil  or 
under  clay,  and  between  the  two,  a mass  of  decaying  vegetable 
mould.  If  it  were  not  for  this  decay  a large  portion  of  the  world 
would  be  buried  under  thousands  of  feet  of  dead  trunks  and  vege- 
tation, iustead  of  which,  despite  the  growth  upon  growth  of  gen- 
erations of  forest,  we  have  but  a few  inches  of  black  vegetable 
soil  to  represent  them,  the  rest  having  all  passed  off  into  the  ele- 
ments of  the  air,  and  been  again  and  again  reabsorbed  by  subse- 
quent generations.  Such  is  the  history  of  dry  forests  and  it  is 
obvious  that  from  them  alone,  without  the  assistance  of  some 
other  agency  we  could  never  have  derived  our  thick  coal  beds. 
That  agency  was  water,  proofs  of  whose  existence  in  connection 
with  the  coal-beds  are  very  apparent  in  the  sandstones,  which 
show  a net-work  structure,  as  if  they  had  been  cracked  all  over 
and  the  cracks  filled  up  with  some  harder  substance,  these  are 
fossil  mud-cracks,  the  same  as  we  see  in  the  bed  of  a pond  that  is 
drying  up,  tracks  of  worms  are  found,  and  in  some  coal  fields 
foot-prints  of  saurians  that  crawled  over  the  mud.  Though  the 
elements  of  vegetation  pass  off  into  the  invisible  air  on  dry  land, 
if  you  submerge  these  trees  and  vegetation  in  water,  they  retain 
many  of  their  elements,  especially  carbon,  the  tree  only  rots  in 
part,  becomes  water-logged,  and  gradually  sinks  into  the  soft 
blackened  substance  of  peat,  and  if  afterward  by  sinking  of  the 
land,  it  is  in  this  state  covered  deep  with  sediments,  it  is  turned 
into  coal.  The  conditions  most  favorable  for  coal  formations, 
appear  to  be,  a damp,  moist,  warm  atmosphere,  a rank  vegetation, 
low-lying  swampy  land  receiving  sediment  washed  into  it  from 
higher  land,  gradually  subsiding  beneath  the  waters  of  a great 
lake  or  sea.  The  northern  hemisphere  contains  the  most  coal, 
such  as  northern  Europe,  America,  and  China,  the  largest  but 
least  known  fields  are. said  to  be  in  China. 

Chemists  tell  us  that  vegetable  matter  buried  in  the  earth, 
exposed  to  moisture  and  excluded  from  the  air,  decomposes 
slowly,  evolving  carbon  dioxide,  and  parting  with  some  of  its 
original  oxygen,  in  this  way  vegetation  is  gradually  changed  to 
“lignite,”  containing  a greater  proportion  of  hydrogen  than  wood, 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


21 


continued  decomposition  aided  by  pressure  and  some  heat 
changes  lignite  to  bituminous  coal  by  discharge  of  carburetted 
hydrogen,  that  is,  the  common  gas  we  illuminate  our  streets  with. 
The  inflammable  gases  escaping  from  coal,  causing  such  fearful 
accidents  in  mines,  contain  light  carburetted  hydrogen  and  olefi- 
ant gas.  The  disengagement  of  all  these  volatile  gases  by  slowly 
applied  heat,  gradually  transforms  the  bituminous  coal  into  anth- 
racite, and  the  next  and  last  stage  is  graphite. 

The  extent  to  which  coal  has  thus  been  changed  by  parting 
with  its  gas,  is  related  to  the  amount  of  disturbance  undergone 
by  the  strata  enclosing  it,  the  numerous  cracks  thus  formed  act- 
ing as  escapes  for  the  gas.  The  increased  heat  derived  from  the 
interior  is  also  an  important  factor  in  the  change.  This,  as  we 
have  shown,  is  well  illustrated  in  the  region  about  Crested  Butte 
and  Glenwood  in  Colorado,  it  is  also  forcibly  exemplified  in  the 
coal  fields  of  the  eastern  states.  The  coal  strata  west  of  the  Alle- 
ghanies  are  horizontal,  and  the  coal  bituminous,  but  going  south- 
east, the  strata  become  disturbed,  and  the  same  seam  progres- 
sively debituminized,  in  proportion  to  the  greater  folding  of  the 
rocks.  At  first  the  coal  yields  50  per  cent,  hydrogen,  oxygen, 
and  volatiles,  then  40  per  cent,  as  the  folds  commence,  till  on 
entering  the  mountains,  where  the  folding  and  faulting  are  at 
their  maximum,  these  fall  to  6 per  cent,  (anthracite). 


The  gradual  change  from  wood  to  anthracite  is 
ollowing  analyses  from  Huxley’s  physiography. 

Carbon.  Hydrogen. 

shown  in  the 

Oxygen 
and  Nitrogen. 

Wood  (oak)  .... 

48.94 

5-94 

45.12 

Peat 

5562 

6 88 

37-50 

Lignite  

Bituminous  coal  (New- 

6994 

5-95 

24  1 1 

castle,  England)  . . 

88.42 

5.61 

5-97 

Steam  coal  (Wales) . . 

92. 10 

5.28 

2.62 

Anthracite 

94.05 

3-38 

2.57 

NATURAL  HISTORY  OF  COLORADO  COAL  BEDS. 

The  coal  beds  of  the  Laramie  group  in  Colorado  were 
formed  at  a time  when  the  continent  and  these  mountains  (then 
only  islands)  were  gradually  rising  from  a protracted  marine 


22 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


condition  that  had  more  or  less  prevailed  in  previous  periods, 
from  the  Silurian  to  the  Upper  Cretaceous.  An  interior  arm  of  the 
sea,  dividing  the  continent  and  extending  from  the  Gulf  of 
Mexico  to  Alaska,  was  being  drained  off  by  the  elevation  of  the 
lands  east  and  west  of  it,  leaving  as  it  retired  a good  many 
brackish  lakes  behind  it,  to  be  gradually  rinsed  out  and  become 
fresh  as  the  elevation  continued,  by  freshwater  streams  descend- 
ing from  the  higher  lands.  Hence  it  is  that  we  find  brackish 
water- shells,  such  as  oysters,  in  great  abundance  at  Marshall  and 
Newcastle,  generally  near  the  lowest  coal  seams  and  at  the 
beginning  of  the  group;  but  in  the  upper  portions,  such  few 
shells  as  are  found,  are  of  fresh-water  origin.  Along  the  shores 
of  these  lakes  and  the  borders  of  the  retiring  sea  were  peat- 
swamps  fringed  with  luxuriant  semi-tropical  vegetation,  and 
receiving  sediments  from  material  washed  from  the  higher  and 
rising  land.  This  accumulation  of  sediment  was  accompanied  by 
a slow  subsidence  of  the  marsh  area,  the  amount  of  which  may 
be  measured  roughly  by  the  thickness  of  the  beds  represented  in 
the  coal  group.  Thus,  on  the  foothills  east  of  the  range,  it  is 
rarely  as  much  as  1,000  feet;  but  on  the  other  side,  in  north- 
western Colorado,  the  subsidence  must  have  been  greater,  as  we 
have  upwards  of  3,000  feet  of  sandstones  and  shale  in  the 
Laramie  group.  Elevation  of  the  granite  mountain-region  was 
apparently  going  on  at  the  same  time  and  with  about  equal  steps 
with  the  subsidence,  for  we  find  the  Laramie  strata  along  the 
mountain  border  invariably  tilted  up  at  a greater  or  less  angle. 
The  gradual  emergence  of  this  part  of  the  continent  from  the 
domain  of  the  sea  is  beautifully  shown  in  studying  the  strata  a 
little  below  the  coal. 

We  have  below  the  coal  the  enormously  thick  shale-beds  of 
the  marine  Fox-Hills  and  Colorado  Cretaceous  groups;  the 
limestone  of  the  Colorado  group  and  the  fineness  of  the  shales 
show  them  to  represent  the  bottom  of  a moderately  deep  sea; 
the  shells  prove  their  marine  character.  Towards  the  upper  part 
the  shales  become  sandier,  implying  shallower  water;  a great 
abundance  of  shells  are  found  also,  whose  habitat  is  never  in 
very  deep  water,  but  commonly  near  shore.  Finally  the  sandy 
shales  pass  into  thick,  massive;  yellow  sandstone,  in  which  we 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


23 


find  numerous  casts  of  seaweeds  which  grow  near  shore.  A few 
feet  above  this  are  the  shells  of  oysters  and  of  other  shell-fish 
which  frequent  brackish  water;  and  a few  feet  above  them  again 
traces  of  land  vegetation,  followed  by  a coal  seam,  generally  a 
thin  one,  showing  that  land  life,  such  as  trees  and  vegetation, 
were  not  as  yet  abundant;  but  in  a few  feet  more  we  have  a 
heavy  coal  seam,  with  sandstone  beds  above  it  containing  leaf 
fossils  in  abundance,  and  several  other  but  usually  smaller  seams 
to  the  top  of  this  series. 

These  coal-bearing  beds  of  Colorado,  which  are  the  same  in 
general  characteristics  all  the  state  over,  were  called  by  Hayden 
the  Laramie  group,  because  of  their  prominence  in  the  neigh- 
borhood of  Fort  Laramie  in  Wyoming,  where  extensive  coal- 
fields, covering  30,000  square  miles,  have  long  been  developed. 
They  consist  principally  of  sandstone  and  shales,  with  more  or 
less  coal  seams  at  intervals,  and,  as  we  have  said,  are  partly  of 
brackish  and  partly  of  fresh  water  origin.  The  physical  changes 
we  have  alluded  to  “affected,”  says  Dr.  Newberry,  “the  whole 
great  interior  basin  of  the  continent,  as  we  find  the  characters 
and  relation  of  the  Colorado,  Fox-Hills  and  Laramie  groups  to 
be  continuous  along  the  flanks  of  the  Rocky  Mountains  quite 
across  the  State  of  Colorado,  and  from  northern  Wyoming  to 
southern  Chihuahua  in  Old  Mexico.”  And  again,  speaking  of 
the  coal-fields  of  western  Colorado,  he  says:  “This  coal-field  is 
but  the  eastern  margin  of  a sheet  of  upper  Cretaceous  rocks, 
which  reaches  across  the  Rocky  Mountains  to  the  Wahsatch, 
everywhere  carrying  coal,  but  the  influences  which  have  given 
such  varieties  and  excellence  to  the  coals  of  western  Colorado, 
viz.,  the  eruption  of  igneous  rocks,  do  not  extend  west,  and  Utah 
coals  are  soft,  less  varied  and  less  pure.” 

The  great  coal  fields  of  the  Eastern  states  belong  to  a far 
earlier  period  of  the  earth’s  history  than  those  of  Colorado ; they 
are  for  the  most  part  in  the  Carboniferous,  whilst  those  of 
Colorado  are  in  the  upper  Cretaceous,  periods  separated  from 
one  another  by  millions  of  years  and  by  thousands  of  feet  of 
rocky  strata.  We  have  the  representatives  of  the  Pennsylvania 
Carboniferous  in  Colorado,  but  it  lies  at  least  5,000  feet  below 


24 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


our  coal-beds.  The  Carboniferous  in  Colorado  is  rarely  pro- 
ductive of  any  coal ; it  consists  principally  of  limestone,  grits, 
sandstone  and  shales,  yielding  us,  however,  material  of  great 
value,  for  some  of  our  most  important  silver  mines,  such  as  those 
of  Aspen  and  Leadville,  are  located  in  this  series.  That  it  is 
related  to  that  in  Pennsylvania  is  evident  from  the  fact  that  we 
find  in  the  middle  group  of  this  series,  among  thick  beds  of  shale 
and  sandstone,  a few  of  the  same  peculiar  fossil  trees  that 
characterize  the  Carboniferous  in  the  Eastern  states  and  the 
world  over,  such  as  the  remains  of  gigantic  reeds  (“  Calamites  ”) 
and  of  curious  trees  called  “ Lepidodendra”;  also  in  a few  cases 
we  find  beds  of  black  carbonaceous  shales,  as  if  coal  had  tried  to 
form,  but  failed  from  lack  of  material;  and  lastly,  in  a few 
localities,  actual  thin  seams  of  good  coal  like  that  of  the  Eastern 
states — in  only  one  or  two  districts,  however,  is  it  within 
minimum  workable  size — and  is  utilized  only  in  places  remote 
from  our  Cretaceous  coal.  Thus  at  Telluride,  in  the  San  Juan 
mountains,  a seam  of  very  good  coal  (three  feet  thick)  is. 
developed  in  small  quantities,  meeting  with  a ready  local  market 
at  the  high  price  of  $\o  per  ton. 

This  shows  us  that  the  Carboniferous  is  with  us,  but  that  the 
circumstances  under  which  it  was  laid  down  in  this  region  were 
different  from  those  in  the  East  and  not  favorable  to  coal- 
making; probably  they  were  more  marine  than  those  in  the 

Mississippi  Valley,  where  such  great  and  valuable  coal  deposits 

exist.  The  trees  and  vegetation  of  the  Carboniferous  were  of  a 
very  different  order  from  those  of  our  Cretaceous,  which  latter 
are  closely  allied  to  those  now  living;  this  may  have  something 
to  do  with  the  different  character  of  the  coal  in  the  two  regions. 
There  were  the  same  swampy,  “watery  woodlands ” and  peat- 
beds  in  both  cases,  but  in  the  Carboniferous  there  was  not  so 
much  high  land  as  in  the  Cretaceous.  The  low-lying  islands 
and  continents  were  covered  with  a dense,  luxuriant  vegetation 
in  the  Carboniferous,  of  a peculiar  kind  and  all  of  a swampy 
character.  Gigantic  tree-ferns,  equally  gigantic  reeds  and  club- 
mosses,  and  other  forms  unlike  any  now  living,  united  with  a 

peaty  undergrowth  to  give  us  those  coal-beds.  In  the  case  of 

our  Cretaceous  beds  there  was  comparatively  high  land  in  the 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


25 


neighborhood,  clothed  with  both  hard  and  soft-wood  trees,  very 
similar  to  those  of  the  present  day.  These,  with  bordering  peat- 
swamps,  gave  us  our  Colorado  coal. 

The  coal  of  the  Eastern  States  being  of  older  age,  has  been 
covered  with  a greater  thickness  of  sedimentary  rocks,  and  for  a 
far  longer  time  than  our  newer  beds,  which  fact,  together  with 
the  heat  engendered  by  depth,  has  concentrated  their  carbon, 
making  them  very  compact  and  of  a superior  quality ; but,  to 
make  up  for  this  deficiency,  our  coals  have  often  been  subjected 
to  greater  heat,  and  to  a certain  amount  of  mechanical  pressure 
by  the  greater  elevation,  disturbances  and  volcanic  eruptions  of 
our  greater  mountain  system,  which  have  brought  about  very 
nearly  the  same  results  in  the  character  of  the  coal,  especially  in 
certain  of  our  districts. 

It  is  often  difficult  to  persuade  Eastern  people,  unacquainted 
with  Colorado,  that  we  have  in  this  and  adjoining  States  coal 
fields  of  greater  area,  with  thicker  seams,  and  often  equally  good 
coal,  as  in  their  time-honored  Eastern  localities.  The  statements 
that  we  have  anthracite  as  good  as  that  of  Pennsylvania,  bitum- 
inous coals  in  beds  of  great  thickness,  comparing  favorably  with 
theirs;  coal  again  of  such  remarkable  purity  that  it  will  yield 
coke  as  good  as  that  of  the  far-famed  Connellsville  field;  all 
these  are  looked  upon  as  exaggerations.  If  these  Western 
States  had  been  discovered  first,  and  had  become  as  thickly  pop- 
ulated as  the  Eastern  States  now  are,  it  is  a question  whether 
Colorado,  Wyoming  and  adjacent  territories  would  not  have  been 
considered  as  the  great  coal  area  of  the  United  States.  We 
stand  now  about  fifth  in  in  the  rank  of  coal-producing  States,  but 
as  to  our  undeveloped  resources,  we  rank  among  the  first. 

When  first  examined  by  Hayden,  many  years  ago,  our  coal- 
fields were  unfortunately  dubbed  “ The  great  lignitic  formation 
of  the  West,”  merely  from  their  geological  position,  seeming  to 
agree  with  that  formation  which  carries  the  inferior  “lignite”  ot 
Europe,  without  any  respect  to  the  character  of  the  coal  contained 
in  these  beds.  Thus,  by  persons  outside  of  Colorado,  our  coal  was 
supposed  to  be  inferior  “brown  lignite,”  which  is  little  better  than 
peat.  It  is  true  that  we  have  a class  of  coals,  locally  distributed 
along  the  plains,  whose  analysis,  from  the  amount  of  fixed  carbon 


26 


GEOLOGY  OF  COLORADO  COAL  FLELDS. 


and  water  shown,  brings  them  within  the  chemical  definition 
of  lignite;  a lignite,  however,  of  a very  superior  quality.  ' 

This  character  of  coal  is  limited  principally  to  one  field,  that 
of  the  Denver  basin,  forming  but  a small  fraction  of  our  coal 
area,  while  from  Canon  City  south  to  Trinidad,  the  same  coal- 
beds are  no  longer  lignitic,  their  per  cent,  of  fixed  carbon,  their 
firmness  and  other  qualities  raising  them  to  the  rank  of  bitumin- 
ous or  semi-bituminous  coals  of  a high  order,  while  again,  the 
same  formation  over  the  range,  all  through  the  western  and 
more  mountainous  portion  of  Colorado,  yields  coal  which, 
beginning  at  bituminous,  ascends  in  the  scale  through  coking 
coal  to  genuine  anthracite.  Dr.  Newberry,  of  Columbia  College, 
who  has  had  perhaps  the  largest  experience  of  any  man  in  the 
coal  fields  of  both  the  Eastern  and  Western  States,  speaking  of 
the  coal-fields  of  northwestern  Colorado,  says:  “They  contain 
sometimes  as  many  as  eight  to  ten  seams  of  coal,  some  of  which 
occasionally  reach  a thickness  of  20  feet  or  more.”*  Often  40  to 
50  feet  of  workable  coal  may  be  seen  in  the  same  section,  and 
this  of  a quality  which  will  compare  with  any  known  in  the 
world  It  should  also  be  said  that,  owing  to  varied  and  peculiar 
conditions,  the  coal  forms  several  varieties,  each  of  which  has  its 
special  uses  in  the  economy  of  civilization.  Here  we  find 
anthracite,  as  hard  and  bright  as  any  of  that  mined  in  Eastern 
Pennsylvania — semi-bituminous  coals  similar  in  composition  to 
those  of  Blossburg,  Cresson  and  Frostburg,  but  more  compact 
and  pleasanter  to  work,  transport  and  use — bituminous  coals 
which  yield  a coke  as  good  as  that  of  Connellsville  or  Durham, 
and  open-burning  or  furnace  coals,  similar  in  character  to  the 
famous  Briar  Hill  coal  of  Ohio,  and  of  equal  value.  Though  so 
unlike  in  other  respects,  these  coals  have  this  in  common,  that 
they  are  of  unusual  purity,  sometimes  containing  two  per  cent., 
and  rarely  more  than  five  per  cent.,  of  ash,  with  little  sulphur  or 
phosphorus. 

Some  approximate  estimates  of  the  areas  covered  by  the 
fields  of  this  western  portion  of  the  continent  will  give  a rough 
idea  of  the  vastness  of  our  coal  resources.  At  least  twenty 
thousand  square  miles  of  Colorado  are  underlaid  by  coal. 


♦One  seam  alone  is  45  feet  thick. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


27 


Texas  has  thirty  thousand  square  miles,  Dakota  one  hundred 
thousand  square  miles.  New  Mexico  has  at  least  six  hundred 
thousand  acres  of  coal,  ranging  from  lignite  to  anthracite  ; 
Wyoming,  twenty  thousand  square  miles;  Montana,  twenty 
thousand  square  miles.  Of  Utah  we  have  no  estimate,  but  it  is 
probably  quite  as  great  as  any  of  the  others. 

It  must  not  be  supposed,  however,  that  all  of  the  coal  in  this 
vast  area  is  available. 

It  is  only  within  the  last  year  or  two  that  people,  both  in  Col- 
orado and  in  the  East,  have  begun  to  recognize  the  magnitude 
and  importance  of  our  coal  fields,  a recognition  arising  partly 
from  the  opening  of  new  railroad  lines,  increased  population,  and 
the  influx  of  Eastern  speculators.  Where  one  or  two  companies 
formerly  enjoyed  the  monopoly  of  nearly  the  whole  coal  trade  and 
coal  fields,  on  the  strength  of  a few  mines,  there  are  now  dozens 
of  companies,  whose  mines  are  scattered  over  the  whole  area, 
and  speculators  are  constantly  on  the  lookout  for  coal  lands, 
some  in  the  proximity  of  already  established  railroad  routes, 
others  in  tracts  of  country  where  they  hope  railroads  may 
eventually  come,  while,  in  addition  to  these,  there  are  hundreds 
of  square  miles  of  coal  field  that  are  not  even  taken  up,  still  less 
developed,  containing  great  bodies  of  coal  outside  of  the  prob- 
able future  line  of  any  railroad  for  a long  time  to  come. 

PROSPECTING  FOR  COAL. 

Nearly  all  the  coal  that  has  been  opened  up  in  Colorado  was 
first  discovered  by  accident,  by  the  digging  of  a well  or  a found- 
ation, or  by  the  outcrop  of  the  coal  itself,  plainly  seen  along  the 
banks  of  some  stream  ; in  fact,  almost  every  stream  that  issues 
from  the  mountains  will  show  more  or  less  coal  at  a certain  point 
along  its  banks.  That  point  is  not  generally  difficult  to  find, 
when  the  strata  are  well  upturned  and  exposed  to  view.  By 
starting  from  the  granite  and  walking  down  stream  across  the 
upturned  hogbacks,  as  shown  in  the  sections  accompanying  this 
work,  you  will  generally  find  next  to  the  granite  a series  of  red 
rocks  (Jura  Trias),  followed  by  a prominent  hogback  of  gray 
sandstone  (Dakota  group),  then  a valley  or  meadow  of  shales 


28 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


(Fox-Hills  group),  and  lastly  an  outcrop  of  white  or  rusty  sand- 
stones (Laramie  group),  among  which  last  you  will  find  the  first 
coal  seam. 

You  will  recognize  the  Laramie  sandstones  by  their  contain- 
ing a good  deal  of  oxide  of  iron,  and  iron  concretions,  together 
with  fossil  mud* cracks,  impressions  of  fossil  leaves,  and  specks 
or  thin  seams  of  lignite,  you  will  find  the  coal  somewhere  within 
a hundred  feet  among  these  sandstones.  Its  appearance  on  the 
surface  will  be  little  more  than  a dark  brown  stain,  but  followed 
down  a few  feet,  it  will  gradually  pass  into  solid  coal. 

Should  the  rocks  in  the  vicinity  be  obscured  by  vegetation, 
soil,  or  surface  drift,  you  will  rarely  find  the  coal  formation  less 
than  a mile  from  the  granite  mountains,  and  often  more  than  that, 
as  a thickness  of  from  five  to  ten  thousand  feet  of  upturned 
strata  usually  intervenes  between  it  and  the  granite.  If  any  of 
these  strata  are  exposed,  such  as  the  Dakota  hogback,  you  know 
that  the  coal  lies  still  above  it  (geologically)  by  perhaps  half  a 
mile;  if  you  find  a limestone  or  shale  with  marine  shells,  you 
may  be  pretty  sure  you  are  in  the  Colorado  or  Fox-Hill  group, 
and  that  the  coal  does  not  lie  very  far  above  it. 

On  the  flatter  prairies  or  table  lands,  it  is  to  be  remembered 
that  though  you  may  find  indications  of  fossil-leaves,  and  even 
very  thin  seams  of  coal,  you  may  be  on  the  extreme  upper 
portion  of  the  coal  formation,  or  even  on  the  Tertiary  series  still 
above  that,  and  that  the  main  coal  seams  lie  generally  near  the 
base  of  the  Laramie  group,  probably  one  thousand  feet  below 
you.  A good  deal  of  profitless  boring  and  shafting  has  been 
done  on  the  plains  owing  to  some  well  or  other,  as  at  Denver, 
striking  some  thin  seam  of  coal,  encouraging  prospectors  to  go 
down  in  futile  attempts  to  reach  a larger  and  workable  seam. 

In  the  plateau  region  of  southern  Colorado,  the  coal  is 
generally  so  clearly  shown  in  almost  every  canon,  that  prospect- 
ing is  limited  to  a mere  use  of  your  eyes  and  to  good  judgment 
in  the  choice  of  a seam  or  of  a suitable  location.  For  the  same 
reasons  as  just  given,  the  Fox-Hill  shales  with  their  cap  of 
massive  “ fucoidal”  sandstone,  like  the  “ farewell  rock”  of  English 
coal  miners,  should  generally  be  considered  as  the  limit  down- 
wards of  the  coal,  and  all  prospecting  should  be  done  on  strata 
lying  above  it. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


29 


If  coal  seams  are  lost  by  faults,  the  common  rule  “ that  the 
foot  wall  of  the  fault  rises,  and  carries  up  the  coal  with  it,  while 
the  hanging  wall  similarly  fails,”  may  be  generally  followed  to 
advantage.  In  southwestern  Colorado  the  prominent  yellow 
“ fucoidal  ” sandstone,  capping  the  shales  of  that  table  land 
region,  has  been  a useful  guide  to  me  in  knowing  where  coal  does, 
or  does  not  exist. 

If  you  are  looking  for  coking  coal  or  anthracite,  seek  those 
districts  characterized  by  the  greatest  amount  of  overturning  of 
the  strata  and  outpouring  of  eruptive  rocks,  such  as  the  region 
of  the  Elk  mountains.  On  the  prairie  or  flatter  portions  you  will 
generally  find  the  coal  to  be  “lignite”  or  “bituminous”  and 
neither  coking  nor  anthracite,  unless  it  be  locally  made  so  by  the 
presence  of  eruptive  rocks.  After  finding  any  coal  its  quality 
should  be  tested  by  analyses,  especially  as  to  its  coking  qualities, 
for  costly  works  have  been  erected  before  now  in  Colorado  in  the 
neighborhood  of  coal  mines  with  a view  to  producing  coke,  and 
the  coal  was  found  on  trial  not  to  make  coke  at  all.  In  such 
cases  a simple  laboratory  experiment,  taking  but  a few  minutes 
and  costing  a mere  trifle,  would  have  saved  thousands  of  dollars. 

LOCATING  COAL  MINES. 

In  locating  a coal  mine  with  a view  to  development,  the  first 
thing  to  be  considered  is  its  proximity  to  a railroad,  for  without  a 
railroad  a coal  mine  is  helpless.  Having  found  a series  of  coal 
seams  of  workable  size,  i.  e.,  not  less  than  four  feet  thick,  the  best 
seam  should  be  selected,  not  for  its  width  so  much  as  for  its 
freedom  from  partings  of  shale  or  “ bone  ” and  its  physical  or 
other  properties  as  determined  by  analysis,  for  quality  rather  than 
quantity  will  generally  command  the  market,  particularly  if  the 
coal  has  to  be  shipped  to  distant  parts  in  competition  with  others. 
A coal  seam  with  many  shale  partings  at  different  levels  in  the 
seam,  should  be  avoided,  as  it  is  impossible  to  work  the  coal 
entirely  free  from  them,  and  a great  admixture  of  shale  would 
give  a high  per  cent  of  ash,  which  would  reduce  the  value  of  the 
coal,  especially  for  coking  purposes.  Again,  if  there  are  only 
one  or  two  partings,  much  depends  upon  their  position  in  the 
seam,  if  near  the  roof  it  may  be  left  with  perhaps  a foot  of  coal 


30 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


above  it,  to  support  the  roof,  and  the  remainder  of  the  seam  be 
developed ; if  the  parting  occurs  about  the  middle  of  an  average 
size  seam  it  is  inconvenient,  as  in  trying  to  separate  it  from  the 
coal,  the  lower  portion  of  the  seam  must  first  be  worked  back, 
then  the  parting  be  carefully  taken  out  by  itself,  and  lastly  the 
top  portion  worked.  Partings  will  sometimes  gradually  fade  out 
in  portions  of  a mine,  but  at  others  they  will  continue  with 
remarkable  pertinacity  for  a great  distance. 

If  a nearly  horizontal  seam  is  selected,  such  as  those  near 
Trinidad,  it  is  desirable,  if  possible,  to  develop  it  at  some  point 
where  its  gentle  dip  of  a few  degrees  will  be  toward  the  outlet 
and  discharging  point  of  the  mine,  so  that  the  laden  cars  can  be 
drawn  out  on  a gentle  incline  by  gravity  alone,  and  the  empty 
cars  hauled  in  by  mule  power.  If  this  cannot  be  attained,  steam 
power  and  a revolving  wire  cable  is  necessary.  The  rocks  around 
should  be  examined  to  see  if  there  is  any  indication  of  faulting, 
or  whether  dykes  of  lava  cut  through  the  coal  seam.  Again,  it 
is  advisable,  when  possible,  to  open  the  seam  on  the  face  of  a cliff 
or  hillside  at  a convenient  distance  above  the  bottom  of  the 
valley  or  prairie  to  allow  room  for  a dump,  and  also  for  the 
building  of  a raised  tramway,  running  directly  out  of  the  mine  to 
the  tipple,  from  which  the  coal  can  be  shot  down  into  railway 
cars  running  beneath.  Sometimes  the  opening  has  to  be  made 
at  a considerable  height  up  the  hillside,  then  a double  gravity 
tramway  is  necessary  from  the  mine  to  the  tipple. 

In  the  Trinidad  region  most  of  the  mines  are  developed  up 
little  ravines,  which  often  combine  many  of  these  desirable  con- 
ditions. A village  grows  up  about  a coal  mine  of  importance, 
and  this  may  be  located  on  a flat  in  the  valley.  Proximity  to 
water  is  an  important  point,  as  a great  deal  has  to  be  used  at  the 
mine;  and  should  a coking  plant  be  erected  near  by,  an  immense 
amount  of  water  has  to  be  used,  which  at  some  points  in 
Colorado  is  pumped  up  by  steam  from  the  main  river. 

The  main  entry,  at  least,  should  be  wide,  high  and  com- 
modious, whether  the  mine  is  to  be  worked  by  the  “Long-wall” 
or  “Room  and  pillar”  system.  The  tributary  side-levels  need 
not  be  so  roomy;  the  slope  of  the  side  entries,  when  possible, 
should  incline  towards  the  main  entry.  If  the  dip  of  the  strata 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


3i 


be  greater  than  five  or  six  degrees,  the  grade  of  the  track  may 
sometimes  be  lessened  by  running  it  diagonally  across  the  dip 
instead  of  entirely  with  it. 

It  is  not  desirable  as  a rule  to  drive  shafts  or  other  workings 
much  below  the  water  level,  as  the  mine  would  then  be  very  wet, 
needing  pumps,  and  be  much  more  liable  to  fire-damp  and  other 
gases  than  higher  up  the  hill,  where  such  gases  may  have  a 
natural  outlet  through  the  exposed  edges  of  the  strata. 

In  developing  a large  area,  the  workings  should  as  much  as 
possible  be  concentrated  at  one  point  and  not  scattered  over  the 
field,  involving  the  expense  of  a different  plant  for  every  separate 
opening.  If  two  or  three  openings  are  made  at  different  points, 
they  should  be  so  located  as  to  be  connected  with  one  another 
by  tunnels  or  tramways  tributary  to  one  main  discharging 
point. 

Such  are  a few  general  suggestions,  but  much  will  depend  on 
the  character  of  the  location  and  the  judgement  of  the  engineer 
in  planning  the  development  according  to  circumstances. 

The  demand  for  coal  varies  a good  deal  according  to  the 
season,  being  usually  greater  in  Winter  than  Summer;  it  is 
common,  therefore,  to  work  a greater  force  in  the  Winter  than 
the  Summer,  and  in  some  years  more  than  others.  The  rate  of 
wages  varies  in  different  parts  of  the  State,  according  to  the  ease 
or  difficulties  connected  with  the  local  development  and  other 
local  circumstances.  In  nearly  all  the  mines  an  industrious 
miner  can,  if  he  pleases,  make  better  wages  than  at  almost  any 
other  laboring  work  of  a like  nature. 


CHAPTER  II. 


“Denver  Basin”  Coal  Fields. 


Chapter  II. 

THE  "DENVER  BASIN"  COAL  FIELDS. 

By  the  Denver  Basin  we  understand  generally  that  area  of 
country,  with  Denver  as  a center,  lying  between  Boulder  on  the 
north  and  the  Divide  country  around  Sedalia  and  Palmer  Lake 
on  the  south,  and  between  the  foothills  of  the  range  on  the  west, 
and  an  undetermined  line  some  twenty  or  thirty  miles  on  the 
plains  beyond  Denver  to  the  east. 

In  this  area  are  a number  of  coal  mines  tributary  to  Denver 
as  a center.  We  shall  give  first  the  geological  features  of  this 
area,  and  then  describe  in  detail  the  different  coal  districts. 

The  geology  of  this  basin  has  received  a good  deal  of  atten- 
tion, first  by  the  Hayden  Geological  Survey,  and  of  late  by 
Messrs,  Eldridge  and  Cross  of  the  present  survey.  The  writer, 
also,  has  spent  many  years  in  this  basin  studying  its  geology. 

The  Hayden  Survey  sketched  out  in  a masterly  manner  the 
leading  geological  features,  which  have  been  elaborated  by  the 
present  survey.  The  latter  has  also  discovered  some  important 
facts  in  the  divisions  of  the  strata  which  were  not  before  recog- 
nized, such  as  the  existence  of  two  distinct  groups  or  sub- 
divisions of  the  Tertiary,  called  by  them  the  Arapahoe  and 
Denver  Tertiary  beds,  which  were  formerly  included  in  the 
Laramie  Cretaceous  and  supposed  to  be  merely  upper  portions 
of  that  period. 

Portions  of  this  area  are  occupied  by  the  seemingly  hori- 
zontal strata  of  the  plains,  and  portions  by  the  same  strata 
upturned  along  the  mountain  border,  in  a series  of  ridges,  com- 
monly called  “hog-backs.”  The  uplift  of  the  great  range  itself, 
consisting  of  rocks  of  a granitic  type,  is  the  primary  cause  of  this 
movement  among  the  strata. 

Along  the  foothills,  by  reason  of  this  upturning,  we  have  an 
opportunity  of  seeing  clearly  the  nature  of  the  various  strata  that 
are  buried  from  our  sight  beneath  the  plains,  and  can  also  find 


36 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


the  exact  position  among  these  strata  of  that  particular  set  which 
contains  the  coal.  An  approximate  idea  can  thus  be  obtained,  by 
measuring  the  upturned  strata,  of  the  thickness  overlying  the 
coal,  and  at  what  depth  it  might  be  expected  beneath  the 
prairie. 

DESCRIPTION  OF  THE  GENERALIZED  SECTION. (PLATE  II.) 

In  the  generalized  section  we  have  endeavored  to  show  these 
points,  and  have  also  indicated  the  different  geological  horizons 
upon  which  some  of  our  principal  cities  along  the  plains  and 
foot-hills  are  located,  both  within  and  beyond  the  boundaries  of 
the  Denver  Basin,  also  their  position  relative  to  coal.  In  some 
cases  it  will  appear  that,  by  great  surface  erosion,  they  are 
situated  on  strata  that  lie  far  below  the  coal  horizon,  so  that  if 
borings  were  made  immediately  below  the  streets  of  those  cities, 
coal  would  never  be  encountered.  In  a few  cases  cities  are 
actually  located  above  or  upon  the  coal-beds;  sometimes  they 
are  so  high  above  them  that  it  would  take,  as  in  the  case  of 
Denver,  a bore  over  1,000  feet  deep  to  reach  them;  in  others,  as 
at  Louisville,  the  coal  lies  but  a few  hundred  feet  beneath  the 
houses  of  the  town.  It  must  be  observed  here  that  we  confine 
ourselves  to  the  exact  locations  of  the  cities  themselves,  for  in 
several  cases,  cities  are  located  near  coal-beds,  as  Trinidad  for 
example  (which  is  in  the  old  bed  of  a river),  below  which  there 
is  no  coal,  while  on  the  bluffs  immediately  above  the  city,  and 
not  two  miles  from  it,  is  one  of  the  finest  coal-fields  in  Colorado. 
We  have  also  taken  the  opportunity,  in  the  same  manner  as  with 
the  coal,  to  show  what  other  products  of  econom'c  importance 
are  to  be  found  at  certain  horizons,  such  as  the  horizon  of  oil,  of 
flux-limestone,  of  fire-clay  and  building-stone.  By  referring  the 
horizontal  line  to  the  place  where  it  upturns  against  the  moun- 
tains, the  relative  position  of  any  particular  stratum  can  be 
clearly  seen.  Thus  Canon  City  is  located  on  horizontal  shales 
overlying  the  Cretaceous  flux-limestones,  which  are  upturned 
only  a few  hundred  yards  from  the  outskirts  of  the  city,  and  are 
extensively  quarried  close  to  the  penitentiary.  From  this 
diagram  may  be  seen  what  would  be  found  at  certain  available 
depths  immediately  below  Denver,  and  what  lies  too  deep  for 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


37 


our  means  of  boring.  From  ignorance  of  such  geological  facts, 
borings  for  coal  have  often  been  made  and  money  expended, 
where  a knowledge  of  the  strata  would  show  that  no  coal  could 
be  found,  either  by  the  location  of  the  bore  (as  for  instance  on 
the  Divide)  being  too  high  above  the  coal  to  reach  it,  or  as  in  the 
case  of  Pueblo,  being  below  the  coal,  making  the  task  hopeless. 

The  dotted  lines  in  the  upper  part  of  the  diagram  show  some 
of  the  strata  that  once  existed  over  this  area  in  great  thickness 
and  have  been  removed  by  erosion. 

DESCRIPTION  OF  STRATA  OF  DENVER  BASIN. 

We  will  now  describe  the  strata,  beginning  from  the  bottom. 
Were  we  in  the  field  we  could  best  do  this  at  the  outlet  of  one 
of  our  canons,  such  as  that  of  Bear  creek,  Clear  creek,  Ralston 
or  Boulder,  where  streams  have  cut  deep  through  the  upturned 
strata  of  the  hogbacks,  and  shown  the  character  of  each  stratum 
or  group  of  strata,  as  clearly  as  a row  of  books  on  a library  shelf. 

Beginning  with  the  granitic  mountains  which  belong  to  the 
Archaean  age,  as  our  starting  point  in  the  Denver  Basin,  the  first 
set  of  strata  we  find  leaning  upon  them  are  the  Triassic  red 
sandstones.  (The  Silurian  and  Carboniferous  are  not  exposed  in 
the  Denver  Basin,  but  are  found  further  south  at  Manitou). 

Next  come  the  Jurassic  variegated  marls,  clays  and  sandstones, 
followed  by  the  Cretaceous,  with  its  beds  of  sandstone,  limestone, 
and  enormous  thickness  of  shale,  aud  lastly  the  Tertiary,  consist- 
ing of  conglomerates,  sandstones  and  shales;  we  may  add  yet 
another  group,  capping  and  often  concealing  all  the  others,  viz., 
the  Quaternary,  consisting  of  cobble  stones,  pebbles,  gravel  and 
clays,  strewn  over  the  surface  by  glaciers,  rivers  and  lakes. 

It  is  to  be  observed  that  though  we  are  treating  of  the  Denver 
Basin,  the  same  set  of  strata,  and  many  of  the  same  geological 
features,  are  repeated  again  and  again  in  different  parts  of  the 
State,  as  will  be  seen  by  comparing  the  various  sections  accom- 
panying our  reports  on  the  different  coal  districts.  The  thick- 
nesses may  differ  locally,  but  the  leading  characteristics  of  the 
rocks  remain  much  the  same  throughout  the  State,  so  that  a 
section  once  thoroughly  mastered  at  one  locality  is  a key  to  all 
the  rest. 


38 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


ARCHAEAN  AGE. 

The  rocks  of  this  age  constitute  the  great  mass  of  the  moun- 
tains proper,  and  consist  mainly  of  gneisses,  schists,  and  some 
massive  granite.  Of  late  attention  has  been  drawn  to  our  fine 
red  and  gray  granite  as  a building  stone.  The  rocks  of  this  age 
also  carry  much  of  our  precious  minerals  in  fissure  veins. 

THE  TRIAS. 

Resting  on  the  Archaean  with  a easterly  dip  of  from  thirty  to 
forty-five  degrees,  are  a series  of  beds  characterized  by  their  red 
tint.  Eldridge  includes  in  the  Trias  all  the  red  beds  between  the 
granite  and  the  paler  tinted,  softer  shales  of  the  Atlantosaurus 
beds,  which  last  alone  he  seems  to  consider  as  proven  Jurassic. 
In  the  classification  of  the  Hayden  survey  we  used  to  call  the 
massive  beds  Trias,  and  class  the  softer  red  beds  with  their 
included  limestones  and  gypsum  among  the  Jurassic.  He  divides 
the  Trias  into  two  groups,  the  lower  consisting  of  about  1500 
feet  of  massive  red  conglomerate,  capped  by  a cream-colored 
masssive  quartzose  sandstone,  with  gritty  layers,  and  near  the  top 
small,  ferruginous  concretions,  which,  by  weathering  out,  give  a 
singular  pitted  appearance  to  the  rock.  The  upper  600  feet 
consist  of  fine  brick  red  sandstones  and  shales,  with  narrow 
intercalations  of  limestone  near  its  base,  also  variegated  clays, 
layers  of  gypsum  and  pinkish  sandstone. 

From  the  Trias  fine  red  building  sandstone  is  obtained  at  the 
Glencoe  quarries  on  Ralston  creek,  and  at  Morrison  on  Bear 
creek,  also  white  siliceous  sandstone  for  glass  manufacture.  The 
limestone,  also,  is  quarried  and  burnt  along  the  foothills. 

No  fossils  have  been  discovered  in  this  series  in  the  Denver 
basin,  but  the  writer  found  some  fossil  leaves  and  insects  near 
Fairplay,  (South  park),  which  by  some  geologists  are  attributed 
to  the  Trias  and  by  others  to  the  Permian. 

THE  JURASSIC. 

If  we  restrict  the  Jurassic  to  that  series  of  beds  in  which  the 
Atlantosaurus  or  great  Dinosaur  remains  were  discovered  by  the 
writer  some  years  ago,  then  the  series  is  not  more  than  200  feet 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


39 


thick,  and  consists  principally  of  marly  clays  and  shales  of  a pale, 
ashen,  greenish  or  maroon  tint,  overlaid  by  the  brown  “ saurian 
sandstone.”  This  sandstone,  between  ten  and  twenty  feet  thick, 
is  characterized  by  little  white  spots  and  concretions  of  clay ; it 
was  in  this  that  we  first  discovered  the  bones  of  the  Dinosaurs, 
or  great  lizards,  at  Morrison,  afterwards  we  found  them  continuing 
down  into  the  clay.  We  found  fragments  of  bone  at  the  bottom 
of  the  “ hogback  ” and  traced  them  up  to  the  sandstone  ledge 
Whence  they  had  fallen.  We  dug  out  parts  of  several  monsters, 
one  of  them  was  at  least  eighty  feet  long  and  stood  twenty-five 
feet  high,  its  thigh  bone  was  between  eight  and  nine  feet  long; 
these  are  the  largest  known  land  animals.  The  Atlantosaurus 
was  a hugh  lizard,  something  like  a gigantic  alligator,  with  a long, 
thick  neck  and  small  head,  a long,  powerful  tail,  and  a body  of 
elephantine  proportions,  mounted  on  stout,  strong  legs.  Its 
habits  were  herbivorous  like  the  hippopotamus.  Another  smaller 
species  was  covered  with  coats  of  mail,  armed  with  long  spikes. 
The  remains  of  turtles,  crocodiles,  fishes,  and  a few  fresh-water 
shells  were  found  with  these  bones ; the  remains  are  all  in  the 
Yale  museum.  The  beds  are  of  fresh-water  origin  and  continue 
to  the  north  into  Wyoming  and  to  the  south  to  Canon  City.  In 
Wyoming,  below  the  Dinosaur  beds,  we  found  marine  Jurassic 
fossils,  such  as  the  skeletons  of  the  Icthyosaurus,  (Sauranodon), 
or  fish-lizard,  also  Belemnites,  (the  internal  shells  of  cuttle  fish), 
Ammonites,  Nautilus,  and  other  marine  shells ; in  that  region 
there  appears  to  be  a lower  marine  group  in  the  Jurassic  as  well 
as  an  upper,  fresh-water  one. 

The  Jurassic  is  remarkable  as  the  horizon  in  which  petroleum 
was  first  found  in  Colorado,  on  Oil  creek,  ten  miles  north  of 
Canon  City,  many  years  ago  ; the  horizon  which  at  present  yields 
so  much  oil  at  Florence  is  in  the  Fox-Hills’  group  in  the 
Cretaceous. 

THE  CRETACEOUS. 

This  great  series  was  divided  by  Hayden  into  six  groups  from 
peculiar  characteristics  in  each  group,  which  he  named  respect- 
ively the  Dakota,  Fort  Benton,  Niobrara,  Fort  Pierre,  Fox-Hill, 
and  Laramie,  from  localities  where  he  happened  to  study  them,  or 
where  they  were  typically  shown ; the  present  geological  survey 


40 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


makes  only  four  divisions,  the  Dakota,  Colorado,  Fox-Hills  and 
Laramie,  the  Fort  Benton  and  Niobrara  being  included  in  the 
Colorado,  and  the  Fox-Hills  and  Fort  Pierre  in  the  Fox-Hill 
group. 

DAKOTA  GROUP. 

This  is  the  basal  member  of  the  Cretaceous  and  consists  of  two 
hundred  to  three  hundred  feet  of  hard  gray  sandstone,  underlaid 
by  a conglomerate  composed  of  fine  pebbles  of  quartz,  gray  jaspar 
and  chert,  firmly  cemented  together  by  a siliceous  cement.  Silurian 
fossil  corals  are  sometimes  found  as  pebbles  in  this  conglomerate. 
Fossil  net-veined  leaves  of  the  first  Dicotyledonous  trees  known 
to  have  existed  on  this  planet  are  found  in  the  sandstones.  The 
grogp  is  of  fresh  water  origin.  These  sandstones  being  of 
superior  hardness  resist  erosion  and  form  prominent  hogbacks 
among  the  foothills.  A bed  of  dark  blue-gray  fireclay,  five  to  ten 
feet  thick,  of  excellent  quality,  lies  in  the  middle  of  this  group 
and  is  quarried  near  Golden  for  making  firebricks  which  are 
exported  all  over  the  West  for  smelting  furnaces  and  other 
purposes,  and  are  but  little  inferior  to  the  celebrated  Welsh  Dinas 
brick.  The  sandstones  are  quarried  for  building  stone  and  also 
make  good  grindstones. 


COLORADO  GROUP. 

The  lower  portion  of  this  group  consists  of  four  hundred  to 
five  hundred  feet  of  finely  laminated  black  shales,  with  some 
thin  beds  of  limestone;  the  upper  portion,  of  a bed  of  limestone, 
forty  feet  thick,  overlaid  by  shales  of  a pale  yellow  tint  with 
some  gypsum.  The  limestone  of  this  group,  being  nearly  pure 
carbonate  of  lime,  is  extensively  quarried  for  “flux”  for  the 
smelters.  Scales  of  fishes,  oyster  shells  and  shells  of  Inocerami, 
the  latter  not  unlike  large  clam-shells,  often  as  big  as  a saucer, 
are  very  characteristic.  The  entire  group  is  about  seven  hundred 
feet  thick ; it  is  of  marine  origin,  as  shown  by  the  fossils  and  by 
the  presence  of  limestone. 

FOX-HILLS  GROUP. 

This  very  thick  group  consists  largely  of  shales,  some  sand- 
stones and  thin  limestones.  It  varies  in  thickness,  but,  according 


% 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  41 

to  Eldridge,  maintains  an  average  throughout  the  Denver  Basin 
of  eight  thousand  seven  hundred  feet,  or  one  and  a-half  miles. 
At  the  top  of  the  group  the  shales  become  sandier  and  pass 
gradually  into  a sandstone,  sometimes  quite  massive,  of  a 
yellowish  color  composed  of  quartz  and  mica.  This  belt  of 
sandstone  is  very  persistent  and  usually  lies  at  no  great  distance 
below  the  Laramie  coal ; generally  it  is  full  of  many  varieties  of 
marine  fossil-shells,  such  as  Cardium,  Mactra,  Tellina,  Tancredia, 
Callista,  Anchura,  Nucula,  Mytilus  and  Turritella.  Some  of 
these  shells  resemble  clams  and  cockles ; others  are  spiral- 
shaped, like  snails.  A fine  development  of  this  sandstone  may 
be  seen  at  Fossil  Creek,  near  Fort  Collins,  where  innumerable 
shells  are  contained  in  cannon-ball  concretions  in  the  sandstone. 
It  is  the  upper  portion  of  this  massive  sandstone  which  we  often 
mention  in  the  course  of  this  report  as  containing  impressions  of 
sea-weed.  The  scientific  name  of  sea- weed  is  Fucus,  and  this 
variety  is  called  Halymenites,  hence  Hayden  and  others  speak  of 
the  sandstone  sometimes  as  the  Fucoidal  and  sometimes  as  the 
Halymenites  sandstone.  Its  importance  lies  in  its  being  the 
“ bedrock  ” landmark  of  the  coal,  for  the  coal  generally  lies  a 
few  feet  above  this  sandstone  and  is  very  rarely  found  below  it. 
The  entire  group  is  of  marine  origin.  Its  economic  value  con- 
sists in  its  being  the  main  oil-horizon  of  the  State,  as  developed 
at  Florence  near  Canon  City.  The  wells  there  begin  near  the 
top  of  the  group,  a few  feet  below  the  “fucoidal”  sandstone,  and 
penetrate  the  shale  for  between  fourteen  hundred  and  two  thou- 
sand feet,  and  then  strike  a porous,  sandy  layer,  from  which 
arise  salt  water,  gas  and  oil  together.  As  this  Fox-Hills  group 
is  a very  common  formation  in  Colorado  and  covers  large  areas, 
it  is  probable  that  other  oil  fields,  besides  those  of  Florence,  will 
be  discovered  in  it  in  the  future.  The  fucoidal  sandstone  at  Oak 
Creek,  Trinidad  and  other  localities  furnishes  some  of  our  best 
yellow  building  sandstone. 

LARAMIE  (COAL-BEARING  GROUP). 

This  group  occurs  all  over  the  Denver  Basin.  At  the  base  of 
it  is  a series  of  heavy  bedded  sandstones,  composed  of  clear, 
glassy  quartz,  one  hundred  to  two  hundred  feet  or  more  thick,, 


# 


42 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


followed  above  by  four  hundred  to  five  hundred  feet  of  varie- 
gated clays  and  nodular  ironstone  concretions,  containing  plant 
remains.  Along  the  foothills  at  Louisville,  Marshall,  Erie  and 
Golden  the  coal-beds  are  associated  with  the  lower  basal  sand- 
stones, but  at  Scranton,  twenty  miles  east  of  Denver,  the  coal  is 
in  the  upper  or  shaly  series. 


TERTIARY. 

ARAPAHOE  GROUP. 

For  the  recognition  of  these  and  the  overlying  Denver  beds 
as  a distinct  formation  from  the  Laramie  Cretaceous,  we  are 
indebted  to  the  researches  of  Messrs.  Eldridge  and  Cross.  They 
found  that  these  beds  lie  unconformably  on  the  Laramie,  the 
materials  of  which  they  are  composed,  in  the  case  of  the  Denver 
beds,  differing  remarkably  from  those  composing  the  Cretaceous. 

The  Arapahoe  beds  are  the  lowest  of  three  Tertiary  groups ; 
they  were  first  ealled  Willow  creek  from  being  shown  very 
plainly  on  Willow  creek,  south  of  the  Platte,  the  name  being  since 
changed  to  Arapahoe.  At  the  base  is  either  a thick  conglom- 
erate or  a gritty  sandstone,  according  to  distance  from  the  shore 
line  of  foothills ; this  is  overlaid  by  gray  shales  with  lenticular 
masses  of  hard  quartzose  sandstones  and  ironstone.  The  thick- 
ness of  the  group  is  from  600  to  1200  feet,  the  basal  conglom- 
erate is  sometimes  200  and  more  feet  thick,  composed  of  pebbles 
derived  from  all  the  underlying  formations  even  down  to  the 
Carboniferous,  for  pebbles  with  Carboniferous  corals,  (Beaumontia) 
are  sometimes  found  in  it.  The  pebbles  have  been  silicified  and 
are  principally  jaspars,  agates,  flints  and  petrified  wood.  The 
metamorphism  of  these  is  most  observable  near  the  old  shore 
line.  The  bones  of  dinosaurs  have  been  found  in  the  conglom- 
erate as  well  as  in  the  Denver  beds  above  them. 

DENVER  BEDS. 

This  Tertiary  formation  lies  in  a basin  hollowed  out  of  the 
underlying  Arapahoe  group ; it  occupies  a portion  of  the  area 
about  the  city  of  Denver  for  400  square  miles. 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


43 


The  conglomerates  and  sandstones  which  form  its  beds  are 
derived  largely  from  fragments  of  andesitic  lava,  of  whose  out- 
pouring and  subsequent  destruction  we  have  no  other  record ; 
this  peculiar  composition  mainly  distinguishes  it  from  underlying 
groups.  The  beds  of  fossil  plants,  so  common  in  the  Table 
mountains,  belong  to  this  formation,  and  a few  vertebrate  remains 
have  been  discovered ; these  are  principally  of  turtles,  crocodiles 
and  dinosaurs.  The  tooth  and  scattered  bones  of  a dinosaur  were 
discovered  by  the  writer  and  Mr.  George  Cannon  in  these  beds  at 
the  base  of  Table  mountain. 

The  lower  portion  of  the  Denver  beds  is  best  studied  in  the 
Table  mountains,  and  the  upper  portion  in  Green  mountain,  near 
Golden.*  The  total  thickness  is  1440  feet,  of  these,  525  feet 
forming  the  upper  part  of  this  mountain  are  a very  coarse  con- 
glemerate  of  cobble-stones  derived  from  all  the  formations.  The 
lower  part  is  of  fine  sandstone,  conglomerates  and  clays,  com- 
posed solely  of  andesitic  material.  Half  way  up  Green  mountain, 
on  the  west  side,  a small  coal  seam  occurs,  composed  of  carbon- 
ized stumps  of  trees,  which  still  retain  their  original  form  and 
texture. 

As  the  top  of  Table  mountain  corresponds  to  the  base  of 
Green  mountain,  if  we  add  the  two  mountains  together  we  obtain 
a complete  section  of  the  entire  Denver  group.  That  the  group 
entered  into  the  general  fold  of  the  mountains  is  shown  by  the 
fact  that  its  lower  members  are  lifted  up  to  verticality  near  the 
base  of  Green  mountain. 

As  to  the  age  of  this  group.  The  Monument  creek  beds  on 
the  Divide,  considered  by  Hayden  as  Tertiary,  lie  above  these 
Denver  beds  and  hence  must  be  of  more  recent  date,  as  further 
shown  by  the  fact  that  they  do  not  enter  into  the  general  fold  as 
the  latter  do.  The#  two  groups  are  separable  by  the  different 
constituents  of  their  rocks,  the  Monument  being  mainly  of 
material  derived  from  the  granite,  the  Denver  beds  from  Ande- 
site. Two-thirds  of  the  Denver  beds  were  removed  by  erosion 
before  the  deposition  of  the  Monument  group.  From  the  absence 
of  all  granitic  elements  in  the  lower  portion  of  the  beds,  Mr.  Cross 
concludes  that  at  that  time,  the  mountains  and  foothills  must 
have  been  overwhelmed  and  covered  up  by  a deluge  of  andesitic 


44 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


lava,  so  that  the  waters  of  the  Denver  lake  could  not  reach  the 
granite,  but  drew  all  the  material  of  the  lake  beds  from  the  lava, 
which  must  have  been  of  great  thickness,  as  the  present  thickness 
of  the  beds  derived  froms  its  detritus  shows.  Of  this  lava  erup- 
tion we  have  no  other  trace,  for  not  an  andesitic  dyke  even  is  to 
be  found  for  a hundred  miles  at  least  from  this  area. 

It  was  not  until  the  waters  of  the  lake  had  cut  through  this 
lava  cap  that  they  could  get  at  the  granite,  and  hence  it  is  only 
in  the  upper  portion  of  these  beds  that  we  find  on  Green  moun- 
tain granitic  boulders  and  pebbles  of  other  rocks,  mingled  with 
those  of  the  lava.  This  eruption  of  Andesite  must  have  occurred 
in  the  interval  between  the  deposition  of  the  Arapahoe  and  Den- 
ver beds.  The  Balsatic  lava,  which  it  present  caps  the  ^Denver 
beds  on  the  Table  mountains  at  Golden,  is  of  later  origin  ; its 
source  is  easily  found  in  a large  dyke  north  of  the  Table  moun- 
tains near  Ralston  creek. 

We  gather  from  these  facts  that,  after  the  Arapahoe  beds 
were  deposited  in  a fresh- water  lake,  a great  deluge  of  lava  issued 
from  some  unknown  volcanic  crack  or  vent,  covering  over,  not 
merely  the  lake,  but  also  the  foothills  and  even  the  granite 
nucleus;  that  this  lava-deluged  country  was  again  covered  by  a 
lake  of  fresh-water,  deriving  its  sands  probably  through  the 
medium  of  rivers  pouring  into  it  from  the  lava  cap  until  that  was 
consumed,  and  the  granite  and  buried  foothills  were  again 
exposed.  During  the  existence  of  these  lakes  a tropical  vegeta- 
tion grew  along  the  shores  and  in  the  marshes,  crocodiles  and 
turtles  frequented  the  swamps,  while  dinosaurs  and  great  mam- 
mals strode  along  on  the  dry  land.  Again,  long  after  these 
events,  a second  outpouring  of  lava  of  a different  variety  issued 
from  a fissure  in  the  ground  near  the  region  of  Ralston  Creek, 
and  the  basalt  from  this  poured  into  the,  perhaps,  still  existing 
waters  of  the  Denver  lake,  or  at  least  over  the  beds  once  accu- 
mulated in  its  basin.  Subsequent  erosion  has  removed  much 
also  of  that  lava  cap,  exposing  its  source  in  the  Ralston  dyke, 
but  sparing  a portion  of  the  cap,  which  now  covers  the  two 
Table  mountains  at  Golden,  to  tell  the  history  of  those  ancient 
contests  for  supremacy  between  fire  and  water. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


45 


STRUCTURAL  PECULIARITIES  OF  THE  DENVER  BASIN. 

The  range  has,  according  to  Eldridge,  a structure  “ en 
echelon,”  resulting  from  folding  on  an  axis,  which  extends 
diagonally  across  the  general  trend  of  the  mountains  in  a direc- 
tion ten  to  twenty  degrees  nearer  north-west  than  that  of  the 
range  itself.  By  this  an  anticlinical  arch  is  formed,  the  northern 
end  of  which  disappears  in  the  range,  while  the  southern  extends 
out  into  the  prairie,  and  owing  to  its  south-eastern  dip,  gradually 
disappears  beneath  its  surface.  Between  the  diverging  southern 
end  of  this  fold  and  the  range  proper  is  an  accompanying  syn- 
clinal trough,  whose  axis  rises  to  the  north-west.  This  structure 
produces  a series  of  offsets  from  east  to  west  in  passing  along  the 
foothills  in  a southerly  direction.  On  Big  and  Little  Thompson, 
at  Ralston  and  South  Boulder,  this  structure  is  well  shown. 

FAULTS. 

The  important  faults  in  this  area  are  due  to  the  forces  which 
uplifted  the  Colorado  range,  and  are  caused  by  lateral  pressure 
at  right  angles  to  its  axis,  the  greater  folds  breaking  in  faults 
parallel  to  their  axes.  At  South  Boulder  a double  peak  has  thus 
been  formed,  and  north  of  Deer  Creek  the  Triassic  strata  are 
twice  repeated  and  a strip  of  granite  is  exposed  at  the  fault  line. 
Another  set  of  faults  are  due  to  forces  independent  of  the  last, 
and  are  exemplified  in  the  neighborhood  of  Coal  creek  and 
South  Boulder  creek.  These  will  be  described  later.  A third 
and  local  kind  result  from  the  extrusion  of  molten  matter,  as 
may  be  seen  in  the  neighborhood  of  the  Ralston  dyke.  The 
faults  in  the  Golden  field  are  the  natural  result  of  the  extreme 
compression  and  parallel  folding  to  which  that  area  was  once 
subjected.  Some  local  nonconformities  also  occur  there,  which 
we  will  describe  hereafter. 

COAL  OF  THE  DENVER  BASIN,  BY  GEO.  ELDRIDGE. 

The  workable  coal  of  the  Denver  field  is  confined  to  the 
Laramie  group,  and  occurs  at  two  widely  separated  horizons,  one 
high  up  in  the  shales,  where  it  is  developed  only  in  the  eastern 


46 


GEOLOGY  OF  COLORADO  COAL  FLELDS. 


part  of  the  field,  the  other  in  the  sandy  series  at  the  base  of  the 
formation,  probably  extending  throughout  the  entire  region. 

The  former  field  is  of  comparatively  small  extent.  The 
presence  of  its  coal  has  been  proved  northward  as  far  as  Scranton 
and  southward  to  Coal  creek  (Upper  Sand  creek),  its  eastern  limits 
still  remaining  undetermined  In  both  the  localities  mentioned 
it  is  within  a short  distance,  overlaid  by  the  Monument  creek 
beds,  though  from  portions  of  the  intermediate  area  this  group 
has  been  eroded,  leaving  the  Laramie  clays  as  the  surface  beds. 
Like  all  other  coals  of  the  Laramie,  the  material  out  of  which  it 
has  been  composed  was  laid  down  in  a shallow  local  basin,  and 
in  its  thickness  varied  greatly  from  place  to  place. 

The  lower  horizon  is  the  important  one  of  the  field,  furnish- 
ing, as  it  does,  nearly  the  entire  amount  of  coal  mined  in  the 
vicinity  of  Denver.  The  distinguishing  features  of  this  horizon 
are  : First,  the  massive  sandstones  at  its  base,  lying  immediately 
upon  the  Fox-Hills,  and  characterized  by  a narrow  median  band 
of  vegetable  remains,  sometimes  altered  to  coal,  the  whole 
attaining  a nearly  uniform  thickness  of  from  120  to  150  feet; 
second,  an  overlying  zone  of  sandstones  and  shales  in  inter- 
changeable proportions,  in  all,  between  fifty  and  seventy-five  feet 
thick,  through  which  occur  the  coal  beds,  and  near  the  base  of 
which  is  found,  at  certain  localities,  a calcareous  sandstone,  from 
one  to  four  feet  thick,  in  which  are  imbedded  great  quantities  of 
fossil  oysters,  (Ostrea  glabra),  together  with  a few  other  charac- 
teristic Laramie  forms ; third,  the  immediate  succession  above  of 
the  great  mass  of  Laramie  clays  and  ironstones  we  have  already 
referred  to. 

The  strata  of  the  lower  coal  horizon  are  exposed  in  a highly 
inclined  position  along  the  foothills  as  far  north  as  Marshall, 
when,  through  the  combined  action  of  upheaval  and  erosion,  they 
are  suddenly  brought  into  a horizontal  position,  or  one  in  which 
they  have  a slight  general  dip  to  the  southeast,  and  the  trend  of 
their  outcrop  becomes  diverted  in  such  a manner  as  to  carry 
them  well  out  on  the  praire  towards  Erie,  several  miles  to  the 
northeast.  In  this  part  of  the  field,  by  reason  of  the  faults,  these 
beds  have  often  suffered  sufficient  elevation  to  bring  their  coals 
either  within  easy  reach  of  the  surface ; or  to  have  caused  them, 
under  the  influence  of  erosion,  to  be  entirely  removed  from 
certain  areas. 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


47 


The  coal  of  this  horizon  occurs  in  several  seams,  usually  four 
to  five,  any  one  of  which  may  develop  to  a workable  size  or 
diminish  to  the  thinest  stratum  of  brown  carbonized  leaves  or 
stems.  The  workable  portions  assume  the  shape  of  shallow 
lenticular  bodies,  from  three  to  ten  feet  thick,  and  from  a quarter 
to  several  miles  in  area ; and  since  their  presence  or  absence  in  a 
certain  locality  depends  entirely  upon  the  ancient  conditions  of 
deposition,  the  greatest  uncertainty  prevails  not  only  as  to  their 
occurrence,  but  also  as  to  their  maintenance  of  even  a workable 
width.  To  this  cause  is  due  the  fact  that  the  valuable  beds  along 
the  foothills  are  so  often  interrupted,  and  that  in  the  prairie 
regions  the  horizon,  though  it  may  be  within  a short  distance  of 
the  surface,  is  completely  barren.  For  the  same  reason,  also,  it 
may  not  be  the  same  seam  that  occurs  in  workable  size  at  the 
several  mines  along  the  foothills,  and  from  their  irregularity  of 
occurrence  and  perhaps  entire  absence,  no  data  exist  for  deter- 
mining the  individual  seam  opened  at  the  various  points.  This 
point  especially  should  be  borne  in  mind  in  all  observations  upon 
the  coal,  the  results  of  which  cannot  but  be  general  for  the  hori- 
zon, instead  of  characteristic  ot  any  single  bed  in  it. 

Regarding  the  presence  of  bodies  of  workable  coal  in  parts 
of  the  field  other  than  those  which  have  already  been  proven,  it 
is  very  probable,  from  the  above  conditions  of  deposition  and  the 
frequency  of  occurrence  of  the  known  bodies  along  the  present 
outcrop  of  the  horizon,  that  other  deposits  of  equal  extent  and 
quality  exist  beneath  the  great  series  of  Tertiary  and  upper 
Laramie  beds  underlying  the  plains.  Their  great  depth,  how- 
ever, which  cannot  be  less  than  between  800  and  1,000  feet,  even 
from  the  very  point  where  they  bend  up  sharply  to  a vertical 
position,  taken  in  connection  with  the  uncertainty  of  their  exist- 
ence under  any  definite  tract  of  land,  should,  in  view  of  the 
quality  of  the  coal  and  of  the  capability  of  the  mines  already 
opened,  not  only  in  this  field  but  also  in  other  parts  of  Colorado, 
prevent  any  deep  prospecting  for  coal  alone  for  years  to  come. 

CLASSIFICATION. 

The  coals  of  the  Denver  Basin  are  discovered,  upon  chemical 
analysis,  to  be  divisible  into  three  distinct  classes,  each  of  which 


48' 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


is  confined  to  a certain  portion  of  the  field  as  at  present 
developed,  and,  moreover,  has  for  that  portion  a remarkable 
uniformity  of  chemical  composition. 

Of  the  divisions  of  the  field  thus  referred  to,  one  embraces 
the  several  areas  under  which  the  beds  of  the  lower  horizon  have 
an  approximately  horizontal  position,  and  includes  the  mines  of 
Marshall,  Louisville,  Davidson,  Canfield,  Erie  and  Coal  creek; 
a second  is  confined  to  the  vertical  beds  of  the  same  horizon, 
along  the  foothills,  and  extends  from  beyond  the  southern  border 
of  the  area  northward  to  Marshall ; while  the  third  conforms  with 
the  area  of  the  upper  coal  horizon,  in  the  vicinity  of  Scranton,  on 
the  Eastern  border. 

Class  I.  resembles  in  its  physical  appearance  many  bitu- 
minous coals  of  the  East,  and  in  its  fuel  ratio  or  the  relation  of 
its  volatile  matter  to  the  fixed  carbon,  might  be  compared  with 
certain  coals  of  the  lower  portion  of  the  Pennsylvania  bituminous 
series,  were  it  not  for  the  proportionately  great  amount  of  water 
it  contains  and  the  fact  that  the  total  percentage  of  its  fuel  con- 
stituents is  much  less  than  that  universally  present  in  the  Eastern 
coal.  Regarding  the  water,  moreover,  it  should  be  added  that  it 
eannot  be  considered  accidental,  but  must  be  looked  upon  as  a 
permanent  characteristic  of  the  coals  of  this  class  throughout  the 
Denver  field.  This  coal  withstands  weathering  well,  and  is  the 
highest  in  economic  value  of  the  coals  about  Denver. 

Class  II.  has,  on  account  of  its  average  composition,  as 
sampled  at  the  present  depth  of  the  mines,  been  given  a separate 
division  in  the  scale,  but  there  is  reason  to  believe  that  its  coals 
are  but  an  altered  condition  of  those  belonging  to  Class  I.,  and 
that,  were  it  possible  to  trace  the  horizon  in  depth,  the  vertical 
beds  into  the  horizontal,  there  would  be  found  a gradual  passage 
in  their  chemical  composition  of  the  one  into  the  other,  Class  I., 
of  course,  having  the  representative  composition  of  a bed  in  its 
original  undisturbed  position.  In  accordance  with  the  very 
probable  causes  of  this  alteration,  the  change  in  composition 
would  take  place  in  the  vicinity  of  the  sharp  folds  at  which  the 
beds  assume  their  different  positions.  The  views  just  expressed 
arise  from  the  facts  that  the  horizontal  beds  have  been  least  sub- 
jected to  physical  changes  since  their  formation,  that  they  and 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  49 

the  vertical  beds  are  of  the  same  horizon,  and  that  in  the  deepest 
mine  of  the  latter  class  (by  some  300  to  400  feet)  the  samples 
from  its  lower  levels  are  found  to  approach,  in  a very  marked 
degree,  the  composition  of  the  horizontal  beds,  the  average  of 
several  analyses  giving : 


Fixed  carbon 42-93 

Volatile  matter 34- 1 9 

Water 18.85 

Ash 3-58 

Sulphur .45 


100.00 


Specific  gravity 1.356 

Fuel  ratio 1.25 


Regarding,  therefore,  these  two  classes  as  originally  one,  a 
most  peculiar  anomaly  occurs  in  the  character  of  the  alteration 
which  the  coal  of  the  vertical  beds  has  undergone ; for,  contrary 
to  the  evidence  of  other  fields  in  like  circumstances,  it  is  found 
that  there  has  been  an  actual  diminution  in  the  per  cent,  of  fixed 
carbon,  with  the  maintenance  of  the  normal  amount  of  volatile 
matter,  an  alteration  the  exact  reverse  of  that  which  usually  takes 
place.  In  explanation  of  this  peculiarity,  it  has  been  suggested 
by  Mr.  Eakins  that,  after  the  lighter  hydro-carbons  of  the  normal 
coal  had  been  driven  off  by  the  increased  pressure,  heat  and 
crushing  of  the  beds  accompanying  the  folding  of  the  Colorado 
range,  their  place  was  supplied  by  the  partial  breaking  up  of  the 
heavier  hydro-carbons  remaining  behind,  and  that  thus  the 
amount  of  carbon  became  diminished  while  the  volatile  matter 
remained  the  same. 

Class  III.  is  characterized  by  the  excess  of  volatile  matter 
over  the  fixed  carbon,  by  the  extremely  large  proportion  of 
water  contained,  and  by  its  high  per  cent,  of  ash.  It  weathers 
most  easily  upon  exposure  to  the  atmosphere,  its  color  becoming 
a brownish  black,  and  there  develops,  sooner  or  later,  throughout 
the  more  exposed  portions  of  the  mass  a decidedly  earthy 
appearance  in  its  character.  It  is,  in  fact,  a lignite,  if  we  regard 
this  term  as  signifying  merely  a position  in  the  scale  of  coals 


50  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

above  peat,  and  below  the  varieties  of  coal  coming  near  the  base 
of  the  recognized  bituminous  series.  It  is  a class  in  which  the 
fuel  ratio  more  often  falls  below  than  exceeds  unity,  at  least  in 
America,  and  it  contains  those  coals  which  are  lowest  in 
economic  value  in  the  Denver  field. 


CHAPTER  III. 


The  Golden  Coal  Beds. 


Chapter  III. 

THE  GOLDEN  COAL  BEDS. 

We  will  commence  with  this  field  as  best  illustrating  the 
geology  of  the  Denver  Basin. 

The  principal  surface  features  are,  the  granitic  Colorado  range 
to  the  west,  cloven  by  the  canon  of  Clear  creek,  and  to  the  east, 
the  Table  mountains,  divided  by  the  waters  of  the  same  stream. 
The  latter  belong  to  the  lower  portion  of  the  Denver  Tertiary 
beds.  The  intervening  valley  between  the  Table  mountains  and 
the  range,  6,000  feet  wide,  is  made  up  partly  of  horizontal,  partly 
of  steeply  dipping  sedimentary  beds.  The  upturned  beds  lie 
nearest  the  range  and  are  3,000  feet  in  thickness,  consisting  of 
members  of  the  Triassic  and  Cretaceous  periods.  The  remain- 
ing space  is  occupied  mainly  by  the  Arapahoe  Tertiary,  overlaid 
by  horizontal  Quaternary  lake  beds  and  drift. 

The  upturned  strata  near  the  flanks  of  the  mountains,  owing 
to  varying  opposite  dips,  open  up  like  a fan,  as  shown  in  plate  III. 
If  we  consider  these  upturned  beds  as  portions  left  by  erosion  of 
a series  of  once  parallel  folds,  shaped  like  an  S,  leaning  towards 
the  range,  we  shall  see  that  their  apparently  opposite  dips  are  the 
result  of  unequal  erosion;  thus  if  the  erosion  spared  the  top  part 
of  the  S that  portion  of  the  fold  would  be  found  leaning  at  a 
gentle  angle  upon  the  granite  and  dipping  east;  if  by  greater 
erosion  due  to  softer  rock  this  top  were  removed,  and  part  of  the 
upper  portion  left,  the  strata  would  appear  to  incline  with  a steep 
overturned  dip  to  the  west;  greater  erosion  still  would  cause 
lower  portions  of  the  fold  to  be  cut  in  the  vertical  portion,  and 
finally  the  flat  or  lowest  horizontal  section  of  the  fold  would  be 
exposed  dipping  gently  east  under  the  prairie.  Thus  we  find  a 
part  of  the  Trias  of  hard  massive  conglomerate,  resting  at  an 
angle  of  twenty  to  thirty  degrees  upon  the  old  granite  shore -line, 
dipping  east  and  representing  the  top  of  the  fold;  the  Fox-Hill 
shales  and  Laramie  sandstones  have  suffered  more  from  erosion 


54  GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 

and  dip  seventy-five  degrees  to  the  west,  as  if  overturned,  repre- 
senting the  middle  of  the  fold,  but  at  700  feet  below  the  surface 
in  the  coal  mine  the  strata  become  vertical  and  begin  to  turn 
gradually  to  the  east;  doubtless  at  a little  greater  depth  they  will 
be  found  practically  horizontal,  passing  down  beneath  the  prairie. 
The  upturned  Arapahoe  Tertiary  beds  above  the  coal  have  had 
the  fold  almost  entirely  removed,  so  that  in  a short  distance  they 
show  only  their  horizontal  portions.  These  severe  foldings  and 
overturnings  have  been  accompanied  by  faults,  which  are  met 
with  occasionally  in  the  coal  mine,  generally  nearer  the  outcrop 
than  at  great  depths. 

UNCONFORMITY  OF  STRATA. 

It  will  be  observed  that,  among  the  series  of  upturned  strata, 
two  or  more  important  groups  are  missing  about  the  middle, 
viz.,  the  Jurassic  and  Dakota-Cretaceous,  locally  for  a space  of 
two  or  three  miles,  for  north  and  south  of  that  interval  we  find 
them  in  their  average  thickness,  but  gradually  getting  thinner 
and  thinner  as  we  approach  Clear  Creek  till  we  lose  sight  of 
them  altogether.  This  may  arise  partly  from  the  extreme  com- 
pression to  which  the  beds  have  been  locally  subjected  in 
endeavoring  to  accommodate  themselves  to  the  sharp  curve  in 
the  outline  of  the  granite  shore  line,  through  the  center  of  which 
Clear  creek  issues  from  its  canon.  Beds  may  have  been  also 
faulted  down  between  other  strata,  overlapped  and  lost  to  sight ; 
or,  again,  we  may  suppose  that  the  nature  of  the  original  shore 
line  was  at  the  time  unfavorable  to  the  deposition  of  thick  sedi- 
ments at  this  point,  as  in  coast  lines  of  the  present  day  we  find 
beaches  deposited  in  bays,  generally,  where  the  shore  line  is  low ; 
if,  on  the  other  hand,  the  cliffs  go  abruptly  down  into  deep  water, 
but  little  sediment  accumulates ; or,  it  may  be  again,  as  Mr. 
Eldridge  explains  in  an  elaborate  manner,  that  actual  uncon- 
formity exists  owing  to  the  presence  of  a steep  fold  or  arch  at  the 
close  of  the  Trias,  whose  axis  would  about  correspond  to  the  line 
of  the  present  Clear  creek,  and  that  this  Triassic  hill  was  inac- 
cessible to  the  waters  of  the  succeeding  periods  of  the  Jurassic 
and  Dakota-Cretaceous. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


55 


STRATIFICATION. 

The  first  set  of  strata  lying  on  the  granite  at  an  angle  of 
thirty  degrees  is  a red  Triassic  conglomerate,  the  pebbles  com- 
posing which  are  derived  from  the  adjacent  granite,  and  are 
large,  as  might  be  expected  from  their  close  proximity  to  the  old 
shore  line,  where  the  waves  dashed  against  the  rocks ; the  thick- 
ness of  this  group  is  about  500  feet.  This  is  followed  above  by  a 
bed  of  limestone  belonging  to  the  Niobrara  group  of  the 
Colorado-Cretaceous,  containing  fossil  oyster  shells.  It  appears, 
then,  that  the  whole  of  the  Jurassic  and  Dakota,  together  with 
part  of  the  Colorado,  are  missing  at  this  point;  a V-shaped, 
grassed-over  interval,  eighty  feet  wide,  lies  between  the  Trias  and 
the  Cretaceous,  the  Cretaceous  dipping  steeply  west,  the  Trias 
east,  hence  at  a point  a short  distance  below  the  surface  the  two 
formations  must  come  together  in  close  conjunction:  It  is  in 
this  eighty  feet  gap  that  the  problem  of  unconformity  lies.  We 
think  it  probable  that  a fault  occurs  at  the  same  point  between 
the  opposing  strata.  Above  the  limestone  are  about  1,000  feet 
of  Fox- Hills  Cretaceous  shales,  with  a few  seams  of  clay  iron- 
stones at  intervals.  Towards  the  upper  portion  these  shales 
become  sandier,  and  we  find  numerous  fossil  marine-shells, 
among  which  little  bivalve  Mactras  and  sections  of  Baculites  are 
very  common.  This  belt  of  shales  dipping  steeply  to  the  west  is 
succeeded  by  the  thick  beds  of  sandstones  and  fire  clay  of  the 
lower  portion  of  the  Laramie  coal  group  for  400  feet ; in  these 
we  find  the  first  indications  of  coal  in  some  half-dozen  little 
seams,  and  towards  the  upper  part  of  the  sandstones  the  White- 
Ash  seam  occurs,  six  to  eight  feet  thick,  with  an  accompanying 
smaller  seam  a few  feet  below  it. 

Above  the  coal  are  three  hundred  feet  of  variegated  clays  and 
some  ironstones.  All  the  strata  from  the  base  of  the  coal  to  the 
top  of  Table  mountain  show  remains  of  fossil  vegetation  and 
occasional  thin  seams  of  lignite. 

These  Laramie  beds  are  succeeded  in  turn  by  the  basal  con- 
glomerate of  the  Arapahoe  Tertiary  composed  of  small  chalce- 
donic  and  granitic  pebbles  cemented  by  iron  oxide.  This  is  the 
last  exposure  for  nearly  3,000  feet  till  we  reach  the  Denver  beds 


56 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


at  the  base  of  Table  mountain,  the  interval  being  covered  by  stiff 
clays,  loose  sands  and  boulders  of  a lacustrine  origin,  belonging 
to  the  Quaternary  age.  Among  the  latter  on  the  north  side  of 
the  creek,  resting  horizontally  on  the  upturned  beds  of  the  coal, 
is  a bed  of  “infusorial”  earth  of  a white  color  and  light  weight, 
about  six  feet  thick,  whose  area  is  undetermined.  Under  the 
microscope  the  characteristic  forms  of  infusorial  shells  are  dis- 
tinctly seen;  the  deposit  is  of  nearly  pure  silica.  The  lake-bed 
clays  make  good  red  brick  and  pressed  brick.  The  Fox-Hill 
shales  supply  plastic  clay  for  the  pottery  works,  while  the  Dakota 
fireclay  makes  the  celebrated  Golden  fire-brick,  the  best  in 
America. 

The  Denver  beds,  which  constitute  the  bulk  of  the  horizontal 
strata  of  the  Table  Mountains  for  600  feet,  consist  of  conglome- 
rates, sandstones,  shales  and  clays,  alternating  with  one  another, 
and  frequently  passing  into  one  another,  composed  of  andesitic 
lava  ; the  color  of  the  strata  is  buff  or  ashen  gray.  The  base  of  the 
formation  and  its  exact  relation  to  the  Arapahoe  series  below  it  is 
obscured  by  lake-beds.  Beds  of  fossil  leaves  are  very  abundant  in 
these  mountains,  especially  in  a zone  about  half  way  up  their  slope ; 
thin  seams  of  lignite  coal  also  occur,  and  much  fossil  wood, 
especially  fragments  or  stumps  of  palm  trees.  These  beds  are 
capped  by  a thickness  of  100  to  250  feet  of  columnar  dolerite 
lava,  which  occurs  in  two  or  three  surface  flows,  each  flow  being 
marked  by  a belt  of  spongy  scoria,  which  once  floated  on  the  top 
of  it.  The  solid  portions  show  a rude  columnar  structure,  cavities 
occur  in  the  scoriaceous  lava,  formed  by  escaping  steam  ; these 
are  lined  with  exquisite  crystals  of  zeolites  such  as  Thomsonite, 
Chabazite,  Natrolite,  Apophyllite,  Analcite,  Mesolite,  Scolecite, 
Laumontite  and  Stilbite,  compounds  of  soda,  lime  and  alumina  in 
different  proportions  derived  from  elements  of  the  lava,  deposited 
by  moisture  infiltrating  through  it  into  the  cavities  left  by  the 
escaping  steam.  These  crystals  are  either  snow  white,  pinkish  or 
transparent,  and  occur  in  various  forms,  some  in  needles  and 
pyramids,  others  in  long  bunches  of  silken  hairs  like  spun-glass, 
others  in  tufts  like  swansdown,  others  again  in  cubes,  or  like 
stars.  Nothing  can  exceed  the  beauty  of  these  tiny  crystal- lined 
cavities,  which  sometimes  contain  in  their  center  a large  crystal 
of  Iceland  spar,  resting  on  a setting  of  the  other  gems. 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


57 


The  source  of  this  lava  was  from  a fissure  filled  by  a large 
dyke  a little  north  ol  the  Table  mountains,  crossing  Ralston 
creek.  The  lava  from  this  flowed  over  the  level  plain  in  a south- 
easterly direction,  covering  the  Denver  Basin  between  Ralston 
and  Bear  creek,  and  in  the  direction  of  Denver. 

All  these  sedimentary  beds  were  formed  by  water  of  some 
kind,  the  red  Triassic  conglomerates  probably  by  the  waves  of 
a saline  lake  or  sea,  the  lower  Cretaceous  by  a shallow  sea 
dividing  the  American  continent  in  two,  from  north  to  south. 
During  all  these  periods  the  continent  was  but  little  above  the 
waves,  and  the  present  Rocky  Mountains  were  but  granite 
islands  or  reefs,  till  the  close  of  the  Fox-Hills  and  the  beginning 
of  the  Laramie,  when  a general  uplift  took  place,  which  was  con- 
tinued through  part  of  the  Tertiary  and  gave  rise  to  a land  and 
fresh  water  condition,  in  which  we  find,  as  in  the  coal-beds,  great 
numbers  of  the  leaves  of  trees  and  land  plants,  all  of  which  are  of 
a semi-tropical  nature,  as  the  presence  of  palmetto  leaves,  for 
example,  clearly  shows.  That  the  beds  of  Table  mountain  were 
laid  down  through  the  medium  of  rivers  and  lakes  of  fresh  water, 
is  shown  by  the  presence  of  fossil  aquatic  plants,  such  as  the 
water-lily  (nelumbium),  reeds  and  sedges.  Numerous  ferns 
(Woodwardia  and  Sphenopteris)  suggest  a marshy  undergrowth, 
among  which,  doubtless,  the  dinosaur,  whose  remains  we  found 
at  the  base  of  South  Table  mountain,  made  his  home.  Higher 
and  drier  land,  however,  must  have  existed,  as  we  find  the  leaves 
of  the  oak,  maple,  poplar,  beech,  elm,  plane-tree,  sweet  gum  and 
magnolia.  Fresh-water  shells  and  bones  of  mammals  are  scarce. 
The  coal  was  derived  from  the  foliage  of  these  trees  mixed  with 
that  of  the  undergrowth,  as  in  peat  swamps  of  the  present  day. 

The  fiery  origin  of  the  andesitic  material,  out  of  which  the 
waters  formed  the  beds  of  Table  mountain,  has  already  been 
alluded  to;  and  the  second  and  later  outburst  of  lava  that  now 
seals  up  those  beds  under  ioo  feet  of  molten  rock,  has  likewise 
been  traced  to  the  dyke  at  Ralston.  It  is  probable  that  cones 
and  craters,  like  those  of  Vesuvius,  may  have  existed  on  top  of 
that  fissure,  all  traces  of  those  loose  masses  of  scoria  and  lava 
having  long  since  been  removed  by  the  denuding  agencies  which 
have  left  such  striking  evidences  of  their  former  power  and 


58 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


presence  in  the  canon  of  Clear  creek  and  in  that  which  divides 
the  Table  mountains  in  twain.  The  horizontal  Quaternary  lake- 
beds  also  show  the  presence  of  wide  lakes  and  bodies  of  water  in 
their  clays,  of  tumultuous  floods  in  their  pebbles  and  boulders, 
and  of  floating  ice  broken  from  the  ends  of  glaciers  higher  up  in 
the  mountains,  which  carried  out  large  boulders  and  masses  of 
granite  on  to  the  waters  of  those  lakes,  and  melting,  strewed 
them  over  the  bottom,  now  the  grassy  prairie.  The  courses  of 
once  broad  rivers  are  shown  by  the  wide  and  ample  channels  of 
the  present  diminished  streams.  The  position  of  a very  still  lake 
is  proved  by  the  infusorial  deposits,  which  are  formed  of  the 
siliceous  coats  of  microscopic  organisms  found  in  ponds  in  the 
present  day. 

The  whole  geological  series  shows  a predominance  of  water 
in  its  construction,  both  marine,  fresh  and  glacial,  interrupted  at 
intervals  by  outbursts  of  lava,  caused  doubtless  by  the  continued 
upward  rise  of  the  great  mountain  mass  which  forced  the  weaker 
strata  along  its  flanks  to  crack,  and  the  molten  fluid  to  pour 
forth.  It  is  observable  that  nearly  all  mountain  chains  of  the 
world  are  similarly  flanked  by  a series  of  volcanic  outbursts,  and 
that  in  Colorado,  on  the  flanks  of  each  separate  chain  or  range, 
we  find  such  phenomena. 

DEVELOPMENT  OF  THE  COAL 

The  coal  seam  is  developed  on  both  sides  of  the  river.  The 
White  Ash  mine  is  on  the  south  side  and  finds  the  main  seam 
from  seven  to  eight  feet  thick,  dipping  for  the  first  few  hundred  feet 
between  seventy-five  and  eighty  degrees  to  the  west.  At  between 
600  and  700  feet  it  becomes  vertical,  and  in  the  last  few  feet  of  the 
730  feet  deep  shaft,  shows  an  inclination  to  turn  gradually  to  the 
east,  doubtless  at  a little  greater  depth  it  will  be  found  horizontal. 
The  mine,  despite  the  steep  dip  of  the  seam,  has  been  developed 
by  a vertical  shaft  which  started  in  137  feet  west  of  the  outcrop, 
and  at  the  present  depth  of  730  feet  is  still  forty-eight  feet  distant 
from  the  seam.  In  the  first  opening  of  the  mine  trouble  was 
encountered  by  not  meeting  the  seam  where  it  was  expected ; the 
reason  of  this  was,  that  the  coal  had  been  faulted  or  thrown  back 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


59 


from  east  to  west,  continuing  down  however,  and  cross-cuts  from 
the  shaft  to  the  eastward  again  found  the  seam,  which  has 
Continued  to  the  present  depth  without  interruption.  From  the 
shaft  short  cross-cuts  are  run  to  the  seam,  and  then  levels  along 
the  strike  of  the  seam,  north  and  south,  at  a vertical  distance 
from  one  another  of  eighty  feet.  The  south  entry  is  800  feet 
the  north  900  feet  long,  the  greatest  length  worked  out  of  the 
north  entries  being  1,400  feet;  of  the  south  800  feet;  eight  levels 
have  been  worked  out.  Below,  that  is,  west  of  the  main  seam, 
at  a distance  of  ten  to  twenty  feet,  is  an  accompanying  smaller 
seam,  three  feet  thick : the  same  little  seam  is  found  across  the 
creek  on  the  north,  four  feet  thick,  and  at  Ralston  (six  miles 
north)  it  is  eight  feet  thick.  Throughout  this  part  of  Colorado,, 
the  main  seam  is  generally  accompanied  by  a smaller  seam. 


CHARACTER  OF  THE  COAL. 

For  about  200  feet  from  the  surface  the  coal  is  soft,  poor  and 
slacks  readily;  from  that  point  downward  it  increases  in  compact- 
ness and  quality,  till  at  the  present  depth  of  730  feet  in  the  White 
Ash  mine  it  is  of  an  almost  flinty  hardness,  due  to  compression, 
partial  metamorphism,  and  absence  of  surface  influence.  During 
the  early  stages  of  the  mine  they  were  obliged  to  mix  superior 
coals  from  Canon  and  Rock  Springs  with  the  White  Ash  coal,  to 
supply  the  heat  necessary  for  the  kilns  of  the  pottery  works;  in 
its  present  condition  the  coal  supplies  all  the  heat  required.  It 
burns  comparatively  slowly,  and  will  keep  in  a fire  well  over 
night,  throws  out  considerable  heat,  and  slacks  but  little  in  the 
coal  bins.  There  is  very  little  shale  mixed  with  the  coal.  It’s 
superiority  over  the  majority  of  coals  of  northern  Colorado  is 
shown  by  the  accompanying  analyses,  and  by  the  practical  tests 
we  have  mentioned.  It  is  unquestionably  the  best  coal  in  this 
part  of  the  State,  and  would  command  a better  market  if  it  were 
only  developed  on  a larger  scale,  the  output  at  present  being  but 
fifty  tons  daily,  or  15,000  per  annum.  At  present  the  market 
is  confined  to  the  local  trade  of  Golden,  and  the  mountain  towns, 
along  the  line  of  Clear  creek. 


6o 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


Analyses  of  coal  from  the  lowest  level  of  the  White  Ash 
mine,  by  Professor  George  C.  Tilden. 

FIRST  ANALYSIS. 

Water 13.89  percent. 

Volatile  matter 43-51  “ 

Fixed  Carbon 37-35  “ 

Ash  (light  yellow) 5.25  “ 

100.00  “ 

Sulphur • 0.59  “ 


SECOND  ANALYSIS. 

From  samples  taken  500  feet  from  the  last. 


Water 

Volatile  matter 

. . . . 38.18 

Fixed  Carbon 

. . . . 43.50 

Ash  (light  vellow)  . . . . 

. . . 5.50 

100.00  “ 

Sulphur 

...  0.595  “ 

Note  — Recently  a fatal  accident  occuired  causing  the  death  of  ten  men  who  were 
, working  at  the  end  of  the  lowest  level  of  the  White  Ash  mine  in  the  direction  of  the 
Loveland  mine.  The  latter  mine  has  for  years  been  full  of  water.  One  of  the  upper  levels 
of  the  White  Ash,  which  if  protracted  would  have  made  connection  with  the  lowest  level 
of  the  Loveland,  has  for  a long  time  been  on  fire,  and  it  is  supposed  that  this  at  last  burnt 
through  into  the  Loveland,  letting  in  the  water  which  ran  down  the  White  Ash  shaft  and 
drowned  the  men  working  in  the  level  below.  The  bodies  of  the  men  have  not  been 
recovered  and  the  mine  has  been  closed  since  the  accident. 


THE  LOVELAND  MINE. 

This  mine  is -on  the  north  bank  of  Clear  creek,  on  the  same 
seam  as  the  White  Ash.  It  is,  however,  thicker  here,  averaging 
nine  to  ten  feet,  and  the  accompanying  seam  four  feet.  The  shaft 
is  263  feet  deep,  the  north  entry  2,000  feet  long,  the  south  1,300. 
About  30,000  tons  have  been  taken  from  this  mine  since  it  was 
opened.  It  has  been  idle  for  some  years  owing  to  lack  of 
operating  capital.  There  are  no  faults  or  other  obstructions  in 
working  this  mine,  and  it  offers  the  best  facilities  for  opening  up 
the  Golden  coal  seam,  owing  to  its  close  proximity  to  the  railroad 
running  up  Clear  creek  canon  from  Denver  to  the  mountain 
towns. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


61 


The  same  coal  seams  are  traceable  by  outcrops  and  develop- 
ments for  many  miles  north  and  south  of  Clear  creek.  To  the 
south,  for  a distance  of  some  twenty  miles  towards  the  Platte 
river,  the  main  seam  appears  of  smaller  dimensions,  but  beyond 
that,  at  the  Cannon  mine,  west  of  Sedalia,  the  seam  is  again  eight 
feet  thick,  stands  vertical,  and  is  said  to  be  of  good  quality.  To 
the  north  of  Clear  creek,  for  about  six  miles,  the  openings  show 
the  seam  to  be  compressed  and  faulted  by  extreme  folding  and 
overturning,  but  on  Ralston  creek  about  eight  miles  north,  where 
the  folding  is  less  and  there  is  a more  expansive  development  of 
the  strata,  the  main  seam  is  sixteen  feet  thick,  and  its  attendant 
seam  eight  feet,  making  twenty-four  feet  of  workable  coal. 
Formerly  these  mines  were  extensively  worked,  but  have  been 
idle  for  some  years ; they  offer  great  facilities  for  future  develop- 
ment. Beyond  Ralston  the  coal  is  easily  traceable  by  its  vertical 
hogbacks  or  outcrops,  in  a sinuous  outline,  till  we  reach  Marshall, 
six  miles  from  Boulder,  where  by  reason  of  erosion  combined 
with  faulting,  the  coal  seams  lie  at  a gentle  angle,  dipping  to  the 
southeast.  There  is  some  prejudice  about  working  these  vertical 
seams  on  the  ground  of  expense.  The  difference  in  favor  of  the 
horizontal  seams,  however,  is  not  so  great  as  supposed,  and  when 
depth  is  attained,  it  is  compensated  by  the  superiority  of  the 
coal.  This  brings  us  near  to  the  northern  limit  of  the  Denver 
basin,  and  we  pass  by  way  of  Erie  to  Louisville  and  examine 
together  the  Louisville  and  Marshall  coal  mines. 


CHAPTER  IV. 


The  Louisville  Coal  Basin. 


» 


Chapter  IV. 

THE  LOUISVILLE  COAL  BASIN. 

This  coal  area  is  about  twenty  miles  from  Denver,  on  the 
east  side  of  the  railroad  between  Denver  and  Boulder.  It  lies  in 
a natural  basin  in  the  prairie,  sloping  to  the  eastward.  The 
average  dip  of  the  surface  of  the  basin  is  to  the  south-east,  at  the 
rate  of  about  one  foot  in  one  hundred  feet,  so  that  at  the  extreme 
limit  of  the  basin,  in  a distance  of  between  three  and  four  miles 
there  is  a fall  of  158  feet.  The  mines  near  that  limit  have  to 
penetrate  to  a greater  depth  to  reach  the  coal  than  they  have  to 
the  westward,  in  the  neighborhood  of  the  town  of  Louisville. 
The  dip  of  the  underlying  strata  appears  to  be  greater  than  the 
dip  of  the  surface. 


TOPOGRAPHY  OF  THE  BASIN. 

About  ten  miles  from  the  town  of  Louisville,  to  the  west,  is 
the  Colorado  Front  range,  cloven  by  the  canons  of  Coal  and 
Boulder  creeks.  These  streams,  issuing  from  the  granite  moun- 
tains, cut  through  a great  thickness  of  sedimentary  strata, 
uplifted  almost  to  verticality  along  the  flanks  of  the  range.  (See 
illustration  of  Marshall  coal-fields,  Plate  IV.) 

The  strata,  for  some  distance  out  from  the  mountain  border, 
appear  to  have  felt  the  influence  of  this  uplift,  for,  for  some  ten 
miles  down  the  course  of  Coal  Creek  we  find  evidence  of  faulting, 
and  the  coal  over  that  distance  is  so  broken  up  that  it  is  not  con- 
venient for  working.  A portion  of  this  disturbed  district,  as  an 
elevated  rolling  prairie,  forms  the  western  boundary  of  the  Louis- 
ville coal  depression.  A gentle  rise  to  the  north-west  also  forms 
the  rim  of  the  basin  in  that  direction.  The  southern  and  eastern 
boundaries  are  defined  by  the  bluffs  forming  the  banks  of  Coal 
Creek.  The  stream  curving  around  toward  the  east  and  north, 
partially  encircles  the  lower  portion  of  the  basin.  These  bluffs 
rise  between  100  and  200  feet  above  the  depressed  flat  of  the 


66 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


Louisville  basin.  The  coal  basin  is  thus  defined  by  natural 
boundaries.  On  two  sides  it  is  further  limited  by  a fault. 

The  basin  is  a long,  oval,  nearly  flat  meadow,  from  three  to 
four  miles  in  length,  by  about  one  to  one  and  a-half  in  breadth. 
There  is  reason  to  believe  that  this  entire  area  is  underlaid  by  a 
bed  of  coal  of  more  or  less  workable  thickness.  The  coal  out- 
crops on  the  bluffs  at  several  points  around  the  edges  of  the 
basin.  The  thickest  and  most  available  portion  of  the  coal-bed 
underlies  the  flat  part  of  the  basin  itself,  as  proved  by  numerous 
borings  at  different  points,  and  by  the  actual  workings  of  the 
mines.  The  coal  is  reached  by  vertical  shafts  varying  from 
180  to  300  feet  in  depth. 

GEOLOGY  OF  THE  BASIN. 

On  examining  the  bluffs  forming  the  southern  and  south- 
eastern banks  of  Coal  Creek,  we  find  them  to  consist  of  heavy- 
bedded  sandstones,  averaging  from  60  to  100  feet  thick.  On  the 
bluffs  these  sandstones  are  nearly  horizontal.  Resting  on  them, 
and  overlaid  by  a few  feet  of  drab  shale,  is  a coal  seam  thirteen 
inches  thick,  forming  the  top  of  the  bluff ; from  this  point  we 
look  down  on  the  flat  coal  basin,  Coal  Creek  flowing  beneath  us 
along  the  base  of  the  bluff.  About  2,000  feet  from  this, 
on  the  open  flat,  is  the  opening  of  the  new  slope  of  the 
Louisville-Welch  mine.  The  coal  there  comes  up  to  the  surface 
and  dips  down  into  the  basin  in  a northerly  direction,  at  an  angle 
at  first  of  52  degrees.  This  dip  gradually  diminishes  with  depth 
until  at  about  300  feet  below  the  surface  it  is  only  3 degrees  to 
the  southeast,  rising  again  gently  toward  the  north. 

The  sandstone  found  below  the  coal  in  this  opening,  together 
with  the  little  13  inch  seam  above  the  sandstone,  correspond  to 
the  partial  section  exposed  on  the  bluffs  100  feet  above  the  basin. 
It  is  evident  then  that  these  two  separated  outcrops  were  once 
connected  by  a fold,  which  by  tension  broke,  and  a “ fault  ” or 
“ slip  ” was  the  result.  The  uplifted  or  constant  side  of  this  fault 
is  represented  by  the  steep  bluff  forming  the  bank  of  Coal  Creek; 
the  fallen  block  of  ground,  by  the  flat  depressed  area  of  the 
Louisville  basin. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


67 


The  actual  line  of  fracture  is  approximately  represented  by 
the  course  of  the  stream,  limiting  the  coal  area  in  a southeast 
direction.  Hence  all  tunnels  driven  in  the  direction  of  the  creek 
will,  on  nearing  the  stream,  be  found  to  abruptly  terminate 
against  a wall  of  sandstone.  The  presence  of  this  fault  does  not 
prevent  the  existence  of  other  coal  areas  across  the  creek  to  the 
south  and  southeast. 

I am  told  that  the  coal  in  that  direction,  bordering  the  creek, 
is  much  broken  up  and  even  stands  vertically,  as  might  be  the 
case  if  the  line  of  fault  follows  the  course  we  have  surmised. 

The  strata  underlying  the  basin  are  not  found  by  under- 
ground development  to  be  as  level  and  undisturbed  as  the 
appearance  on  the  surface  might  imply.  The  average  dip  of  the 
basin  strata  is  from  3 to  5 degrees  to  the  southeast,  but  this 
uniformity  is  occasionally  disturbed  by  a series  of  gentle  “ rolls  ” 
or  undulations,  whose  axes  are  doubtless  parallel  to  the  general 
line  of  the  fault,  the  natural  result  of  compression,  exerted  from 
either  side  of  the  basin,  from  southeast  to  northwest. 

The  amount  of  slip  of  the  fault  is  from  350  to  400  feet,  measur- 
ing from  the  outcrop  of  the  little  13-inch  seam  exposed  near  the 
top  of  the  bluffs,  to  the  position  of  the  same  as  revealed  in  the 
workings  of  the  mine  in  the  depths  of  the  basin. 

But  one  important  coal  seam  is  worked,  varying  in  thickness 
in  different  parts  of  the  field,  from  7 to  14  feet.  The  thickest 
portion,  so  far  as  at  present  known,  appears  to  lie  toward  the 
eastern  limit  of  the  basin,  in  the  vicinity  of  the  village  of  Lafay- 
ette. Borings  from  the  surface  downward  for  some  300  feet 
have  encountered  several  unimportant  seams,  until  the  main  seam 
has  been  reached,  below  which  is  an  interval  of  shale  and  sand- 
stone, and  then  the  13-inch  seam  alluded  to  as  occuring  on  top 
of  the  bluffs,  is  met  with,  below  this  again  is  the  basal  heavy- 
bedded  sandstone,  100  or  more  feet  thick.  This  basal  sandstone 
is  the  extreme  lower  limit  of  the  coal  series.  No  coal,  of 
importance,  throughout  the  State  has  been  found  below  this  well- 
known  massive  yellow  sandstone,  the  coal  miner’s  “bed-rock.” 
It  is  called,  by  geoligists,  the  “ Halymenites  ” or  “ Fucoidal  ” 
sandstone,  from  the  frequent  presence  of  the  fossil  casts  of  what 
is  supposed  to  be  a seaweed  or  Fucoid,  called  Halymenites.  The 


68 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


impressions  are  pitted  and  are  such  as  a corncob  might  have 
left,  a useful  fossil-sign  for  the  miner,  showing  him  the  limit  to 
his  work  of  boring. 

Coal  in  Colorado  is  generally  found  above  this  massive  sand- 
stone, rarely  below  it.  For  below  it  lies  a thickness  of  some 
2,000  feet  or  more  of  barren  shales  containing  sea  shells,  and 
called  the  Colorado  group.  As  this  represents  the  bed  of  the 
Cretaceous  sea,  it  is  not  a likely  set  of  strata  in  which  to  find 
remains  of  land  plants  and  vegetation  that  originated  the  coal 
beds.  We  may  here  add,  that  a bore,  a mile  or  more  deep  below 
the  present  well-known  Laramie  coal  horizon,  would  result  in 
discovering  no  more  coal  than  we  actually  do  find,  so  generally 
near  the  surface,  for  the  underlying  strata  show  very  clearly 
where  they  are  upturned  near  the  flanks  of  the  mountains  in 
admirable  sections,  that  no  coal  exists  for  thousands  of  feet 
between  the  Laramie  coal  horizon  and  the  granite  bed-rock. 

COAL  OPENINGS. 

The  signs  that  led  the  prospectors  to  bore  for  coal  in  the  basin 
were  the  outcrops  in  plain  view  on  the  bluffs.  The  old  Welch 
mine  about  half  a mile  east  of  Louisville  has  a shaft  down  180 
feet,  which  struck  the  main  seam  8 to  io  feet  thick.  This  was 
developed  for  some  years  over  a large  underground  area  by  the 
usual  “room  and  pillar”  system,  and  thousands  of  tons  of  coal 
were  extracted.  “ Gob”  fires  breaking  out,  accompanied  by  a 
series  of  strikes,  (the  latter  appearing  to  constitute  an  essential 
element  in  the  atmosphere  of  these  Boulder  County  coal  districts,) 
the  mine  was  abandoned  and  flooded  with  water.  The  plant, 
much  enlarged,  together  with  a new  outfit  of  some  of  the  most 
powerful  mining  machinery  in  the  country,  was  moved  to  a new 
site  on  the  field,  about  a quarter  of  a mile  east  of  the  old  workings, 
and  nearer  the  centre  of  the  basin.  To  determine  a suitable  loca- 
tion for  the  new  openings  and  to  prove  the  continuity  of  the  coal, 
two  borings  were  made  i,8oo  feet  apart.  At  both  places  the  bores 
recorded  from  7 to  10  feet  of  coal  at  about  200  feet  below  the 
surface.  The  surface  of  the  prairie  being  flat  and  undisturbed 
between  the  two  borings,  it  was  naturally  assumed  that  the  strata 
and  the  coal  in  the  same  interval  below  would  be  correspondingly 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


69 


undisturbed  and  uniform  in  thickness  and  character.  So  without 
much  further  prospecting  the  works  were  moved  to  a site  half-way 
between  the  two  borings,  and  a shaft  was  let  down,  which,  con- 
trary to  expectations,  happened  to  strike  a locally  poor  spot  in  the 
coal  field,  where  the  coal  was  split  up  by  belts  of  shale  and  where 
occurred  one  of  these  “rolls”  we  have  mentioned,  as  probably 
traversing  the  basin  in  parallel  systems.  The  shaft  appears  to 
have  struck  this  roll  on  the  top  of  the  arch,  and  good  coal  is 
hardly  to  be  expected  until  they  get  off  the  axis  on  either  side, 
that  is,  towards  the  north  or  south. 

“ Rolls”  are  common  in  our  Colorado  coal  fields  and  the  point 
of  their  occurrence  is  characterized  by  a local  admixture  of  shale 
and  “bone”  with  the  coal,  and  by  a thinning  of  the  coal  and  cor- 
responding thickening  or  bulging  in  of  the  over  or  underlying 
sandstone  or  shale.  The  cause  of  “rolls”  maybe  two-fold:  first, 
that  while  the  coal  beds  were  forming  in  a marsh,  or  after  they  had 
formed  and  were  consolidated,  they  were  subject  to  erosion  by 
streamlets  or  periodical  freshets,  which  hollowed  out  channels  in 
the  coal  and  afterwards  filled  the  depression  with  sand  or  mud, 
which  subsequently  became  sandstone  or  shale;  secondly,  that 
the  “rolls”  may  be  minor  folds  or  undulating  strata  resulting  from 
lateral  compression  in  the  general  uplift.  The  coal  is  usually 
thinnest  along  the  top  or  axis  of  a “roll”  and  thickens  in  the 
trough  or  either  side  of  it.  We  can  easily  understand  that  intru- 
sions of  shale  and  slate  might  occur  locally  more  abundantly  in 
certain  parts  of  a coal  basin  than  in  others,  and  locally  a coal 
seam  may  be  split  up  and  rendered  valueless  by  belts  of  slate  at 
one  point,  while  but  a few  yards  off  the  same  seam  may  be 
almost  pure.  Not  more  than  2,000  feet  from  this  local 
shaly  “roll”  the  bore  shows  10  feet  of  good  solid  coal.  Again, 
two  miles  southeast  of  it,  at  the  Lafayette  mines,  we  have  14  feet 
of  coal  absolutely  free  from  shale  or  other  partings.  In  the  great 
coal  seam  of  Trinidad  we  find  the  same  phenomena  as  at  Louis- 
ville, in  various  parts  of  the  field  and  often  in  localities  not  far 
distant  from  one  another.  It  is  clear  that  the  persistency,  contin- 
uity, in  thickness  and  character  of  the  seam  cannot  be  relied  upon 
for  any  great  distance  over  a coal  field,  and  that  prospecting  by 
boring  should  generally  be  kept  up  ahead  of  the  underground 


7o 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS 


development.  It  seems  even  advisable  to  put  down  a bore  exactly 
on  the  point  upon  which  we  think  of  shafting  and  erecting  works, 
no  matter  how  undisturbed  and  uniform  the  surface  signs  may 
appear,  nor  how  continuous  the  thickness  of  coal  may  be  in  other 
parts  of  the  field. 

NEW  SLOPE  ON  THE  WELCH  MINE  PROPERTY. 

A promising  opening  has  been  made  about  800  yards  to  the 
southeast  of  the  old  abandoned  Welch  shaft  and  about  2,000  feet 
from  the  new 'works,  It  is  at  the  point  where  the  coal  comes  to 
the  surface  by  reason  of  the  fold  and  fault  I have  mentioned. 
The  coal  is  opened  up  by  an  incline  on  the  seam  of  52  degrees 
dip  for  100  feet,  this  dip  becomes  less  and  less  as  we  descend,  till 
at  150  feet  it  is  about  30  degrees ; at  250,  10  degrees  ; after  that 
the  coal  follows  the  general  dip  of  the  basin,  of  three  degrees  to 
the  southeast.  Across  the  basin  to  the  northwest  the  coal  strata 
appear  to  rise  gently;  the  coal  also  is  said  to  thin  somewhat  in 
that  direction.  The  coal  seam  in  this  slope  is  eight  feet  thick,  of 
good  quality  and  free  from  any  important  seams  of  shale  or  bone. 
Below  the  main  coal  seam  is  about  14  feet  of  yellow  sandstone, 
then  the  13-inch  seam,  and  below  this  for  an  undetermined  depth 
is  basal  Halymenites  sandstone. 

THE  LAFAYETTE  COAL  xMINES. 

From  the  Welch-Louisville  mines  we  follow  down  the  basin 
in  an  easterly  direction  for  two  miles  and  arrive  at  the  coal  village 
of  Lafayette,  which  numbers  about  100  houses.  This  village  has 
sprung  up  within  a few  months  around  three  recently  opened 
coal  mines,  viz:  the  Mitchell,  Cannon  and  Simpson  mines,  whose 
shafts  find  the  coal  seam  14  feet  thick  at  a depth  of  300  feet 
below  the  surface.  The  coal  is  absolutely  free  from  any  parting 
of  clay,  shale  or  bone. 

These  three  mines  being  but  a comparatively  short  distance 
apart,  one  mine  may  be  considered  as  typical  of  the  whole.  We 
chose  the  Simpson  for  examination.  The  coal  is  soft,  easily  worked 
by  room  and  pillar,  and  the  thickness  of  the  seam  permits 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


7i 


the  leaving  of  four  feet  of  coal  to  protect  the  roof,  which  is  gener- 
ally poor  in  this  region,  consisting  of  shale,  or  treacherous  sand- 
stone. This  leaves  a height  of  ten  feet  clear  for  rooms  and 
entries.  The  face  and  end  structure  is  well  shown  in  the  cleavage 
of  the  coal,  the  faces  pointing  north  and  south,  the  ends  east  and 
west.  This  is  one  of  the  finest  looking  coal  seams  we  have  seen 
on  the  eastern  slope  of  the  Front  range.  The  coal,  though  good 
for  general  purposes,  will  not  coke.  The  Harrison  coal  cutting 
machine  is  used  in  the  Simpson,  the  Leg  cutter  in  the  Welch 
mine.  In  the  Welch  mine  is  some  of  the  heaviest  machinery  for 
working  air  compressors  to  be  found  in  Colorado. 

The  Lafayette  mines  seem  to  have  struck  that  part  of  the 
basin  where  the  coal  is  thickest. 

If  we  consider  that  coal  was  formed  in  marshy  basins  under- 
going a slow  subsidence,  we  may  suppose  that  portions  of  such 
basins  would  be  relatively  or  locally  deeper  than  others,  so  if  a 
deep,  thick  portion  of  a coal  field  is  found,  on  general  principles 
we  may  expect  it  to  gradually  thin  out  all  around  this  central 
thick  portion. 

In  this  case  it  may  be  found  thinning  out  to  the  north,  but  on 
the  south  and  southeast  sides,  not  very  far  from  the  present  work- 
ings, the  seam  will  probably  be  cut  off  by  the  fault,  which  follows 
the  course  of  Coal  Creek.  It  diminishes  also  in  thickness  toward 
the  west  at  Louisville,  where  the  Welch  mine  shows  it  to  be  but 
eight  or  ten  feet  thick.  We  are  told  there  is  a tendency  to  thin 
out  toward  the  northwest  also. 

Analysis  of  the  coal  of  the  Simpson  mine,  at  Lafayette,  by 
Prof.  Regis  Chauvenet. 

Water 12.01 

Volatile  matter 35-19 

Fixed  carbon 46.24 

Ash 6.56 

100.00 

Sulphur 1.00 


THE  MARSHALL  COAL  FIELD. 

The  coal  area  is  about  ten  miles  northwest  of  Louisville  and 
six  miles  south  of  Boulder.  A branch  railroad  connects  it  with 


72 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


Louisville.  The  railroad  cuttings  on  the  way  expose,  at  several 
points,  partial  sections  of  the  Laramie  strata,  till  the  road 
emerges  from  the  bluffs  into  a flat,  depressed  area,  the  topography 
of  which  is  the  result  partly  of  faulting,  partly  of  erosion.  The 
bluffs  on  the  southeast  side  of  the  basin  owe  their  steep,  elevated 
position  to  their  being  the  risen  side  of  a fault,  which  passes  through 
the  length  of  the  entire  area.  The  flat,  meadow-like  portion,  at  the 
foot  of  this,  which  is  occupied  by  the  village  and  some  of  the 
principal  workings,  is  the  fallen  side  of  the  fault.  The  rolling 
rounded  bluff,  or  mesa,  on  the  north  side  and  in  the  foreground 
of  the  illustration,  Plate  IV,  which  shows  several  curvilinear  and 
flattish  outcrops  of  sandstone  and  some  coal  exposures,  owes  its 
shape  to  folding,  and  possibly  to  faulting.  Mr.  Eldridge  considers 
this  mesa  a good  example  of  torsional  strains,  with  divergent 
faults,  and  accompanying  folds.  The  line  of  the  main  fault  passes 
along  the  base  of  the  bluffs,  in  the  direction  apparently  marked 
by  the  course  of  a small  stream,  and  very  nearly  by  that  of  the 
railroad  track. 

Mr.  Eldridge  says,  concerning  this  faulted  district:  “The  tri- 
angular area  between  Coal  Creek,  the  mountains,  and  an  east  and 
west  line  a little  north  of  Boulder  Creek,  is  characterized  by 
faultings.  Its  component  lines  of  dislocation  are  grouped  in 
such  a manner  as  to  suggest  a series  of  curvilinear  faults  concen- 
trically arranged,  extending  over  nearly  the  quadrant  of  a circle. 
It  is  probable,  however,  that  the  resultant  curves  are  each  com- 
posed of  three  distinct  linear  faults,  the  southern  trending  N.  60 
E.,  the  middle  N.  30  E.,  and  the  northern  a few  degrees  west  of 
north.” 

In  immediate  proximity  to  the  line  of  fault,  the  strata  of  the 
fallen  and  foot-wall  block  of  ground  has  at  the  edge  been  dragged 
upward  and  bent  back  upon  itself,  in  its  process  of  slipping 
against  the  face  of  the  uplifted  block.  This  reversal  of  strata  is 
shown  in  a little  hog-back  close  to  the  fault  line,  marked  K in 
the  illustration.  The  strata  dip  about  50  degrees  to  the  south, 
while  a few  feet  from  them  the  heavy-bedded  sandstone  of  the 
bluff,  forming  an  abrupt  cliff,  dips  only  5 degrees  in  the  same 
direction.  Such  a sudden  increase  of  dip  of  strata  so  close  to  one 
another  is  a sure  indication  of  a fault.  The  fault  is  encountered 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


73 


in  the  workings  of  the  mines,  the  coal  being  abruptly  cut  off  by  a 
wall  of  sandstone  throughout  the  length  of  the  field,  as  it 
approaches  the  foot  of  the  bluffs  which  form  the  southern  bound- 
ary of  the  basin.  On  ascending  the  bluff,  the  existence  of  the 
fault  is  further  shown  by  the  fact  that  the  strata  composing  the 
ridge  are  duplicates  of  those  found  300  feet  deep  in  the  workings 
of  the  mine  in  the  flat,  meadow  portion.  There  are  two  or  three 
principal  coal  seams  in  this  field,  separated  from  one  another  by 
a few  feet  of  sandstone,  and  underlaid  by  the  massive  yellow 
“fucoidal”  sandstone,  which,  as  we  have  said,  forms  the  base  of 
the  series.  The  idea  that  there  were  four  or  more  important  coal 
seams  on  the  property  arose  from  not  recognizing  the  duplication 
of  strata  and  seams  caused  by  the  faulting.  The  upper  seam  is  8 
to  9 feet  thick,  the  lower  about  4 feet.  The  upper  one  is  that 
which  is  principally  worked. 

On  the  face  of  the  bluff  the  coal  outcrop  shows  evidence  of 
having  been  burnt,  probably  at  a very  early  date.  The  sur- 
rounding sandstone  is  reddened,  and  the  shale  and  clay  reduced 
to  a hard  red  jasper.  The  coal  of  this  area  seems  very  liable  to 
spontaneous  combustion,  for  portions  of  the  field  and  of  the  old 
workings  have  been  burning  for  many  years.  Some  of  the 
workings  on  the  north-west  side,  from  which  the  pillars  were 
withdrawn,  collapsed,  leaving  wide  open  fissures  and  cracks  in 
the  upper  surface.  Soon  after  this,  smoke  was  seen  issuing  from 
the  ground,  and  that  portion  of  the  field  is  now  in  a complete 
state  of  combustion  as  shown  in  the  illustration.  This  long 
continued  combustion  must  have  exhausted  a vast  amount  of 
coal  over  a considerable  portion  of  the  field.  As  we  follow  the 
coal  strata  along  the  bluffs  toward  the  west,  they  come  abruptly 
to  an  end  on  the  edge  of  a basin-like  hollow  of  erosion  between 
them  and  the  lower  geological  strata  of  the  foothills  and  hog- 
backs flanking  the  mountains.  No  coal  is  found  for  an  interval 
of  three  miles  between  this  point  and  the  range.  Similarly  about 
a quarter  of  a mile  to  the  north  the  coal  area  is  cut  off  by  the 
erosion  of  South  Boulder  Creek,  and  terminates  in  a high  bank 
above  that  stream.  No  coal  has  been  found  for  some  miles  to 
the  northwest  in  the  direction  of  Boulder  city.  To  the  south- 
west the  workable  coal  found  in  the  bluffs  is  restricted  by  a 


74  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

faulted  and  broken-up  area  in  the  neighborhood  of  Coal  Creek. 
This  coal  area  is  therefore  circumscribed  on  three  sides  by 
natural  limits.  On  the  east,  however,  (since  as  we  presume  it 
passes  under  the  prairie  and  is  brought  to  light  by  erosion  or 
faulting  far  on  the  plains,  as  at  Erie  or  Louisville,)  there  appears 
no  such  definite  limit.  Coal  might  if  properly  looked  for  be 
found,  we  think,  at  other  points  between  Marshall  and  Louisville,, 
at  varying  depths  probably  not  exceeding  500  feet. 

The  workable  coal  area  is  limited  on  three  sides  to  about  a 
square  mile,  on  the  fourth  side  as  we  have  said  there  appears  to 
be  no  definite  limit.  A good  deal  of  this  area  has  been  worked 
out  in  past  years;  enough  remains,  however,  for  some  years  to 
come.  It  is  an  old  field  with  a portion  worked  out,  a portion 
burnt  out,  and  a good  deal  of  coal  still  left.  The  dip  of  the 
strata  and  the  faulting,  combined  with  surface  erosion,  have 
brought  the  coal  nearer  to  the  surface  on  the  western  and  north- 
western limits  of  the  field,  it  being  there  only  30  to  50  feet  deep. 
Some  of  the  coal  in  this  portion  is  not  sufficiently  good  for 
market,  the  remainder  is  of  good  quality.  The  workings  both 
old  and  new,  are  quite  numerous;  in  the  flat  portion,  the  new 
workings  consist  of  incline  shafts  reaching  the  coal  at  a depth  of 
about  90  feet  from  the  surface,  from  these  radiate  series  of 
entries  and  rooms  following  the  average  dip  of  five  degrees ; in 
this  way  a large  area  has  been  undermined.  The  elevated  area 
is  worked  by  running  tunnels  at  a slight  angle  up  into  the  face 
of  the  bluff  till  the  coal  is  reached  and  followed  down  on  its  dip 
toward  the  south.  The  seam  worked  is  generally  about  eight 
feet  thick  with  local  variations.  It  is  but  little  troubled  by  seams 
of  shale  or  bone.  The  coal,  though  not  coking,  is  good  for 
general  purposes. 

The  strata  immediately  above  the  coal  seam  consist  of  shale 
and  thin-bedded  sandstone  for  about  forty  feet.  On  some  of  the 
sandstones  are  beautiful  impressions  of  ripple  marks  often 
incrusted  by  a thin  layer  of  iron-oxide.  The  sandstones  are 
characterized  by  a net-work  of  fossil  mud-cracks,  caused  by  the 
shrinking  of  the  mud  in  the  process  of  drying  and  consolidation 
in  the  gradual  change  of  the  ancient  coal  swamp  to  its  present 
stony  condition.  The  original  cracks  were  filled  by  some  harder 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


75 


quartzitic  material  often  combined  with  iron-oxide.  Surface 
erosion,  by  removing  the  softer  portion  of  the  sandstone  has  left 
these  harder  seams  in  prominent  relief,  giving  a very  rugged 
aspect  to  the  rocks.  These  sandstones  are  full  of  concretions  of 
iron  which  often  drop  out  and  cover  the  ground  with  nodules, 
showing  a cup  and  ball  structure.  Indications  of  ancient  terres- 
trial vegetation  are  common,  in  the  form  of  leaf  impressions  and 
petrified  stumps.  At  the  eastern  end  of  the  area  the  railroad 
cutting  exposes  a belt  of  five  feet  of  calcareous  sandstone  com- 
posed largely  of  fossil  oyster-shells.  These  lie  a short  distance 
above  the  “ fucoidal  ” sandstone,  and  about  forty  feet  below  a 
small  coal  seam. 

DESCRIPTION  OF  GEOLOGICAL  SECTION,  PLATE  IV. 

The  relation  of  these  Laramie  coal-bearing  strata  to  the 
Cretaceous,  Jurassic,  and  Triassic  periods  lying  geologically 
below  them  is  well  seen  from  the  western  end  of  the  area,  and  is 
also  shown  in  the  illustration.  To  the  West  we  have  the 
Archean  granites  and  gneisses  of  the  mountain  range.  Resting 
upon  them  at  a steep  angle  is  a great  thickness  of  red  Triassic 
sandstone,  partially  metamorphosed,  followed  by  the  Jurassic 
variegated  shales  and  limestones,  and  by  the  hard  white  Dakota 
sandstones.  The  fine  conglomerate  forming  the  base  of  this 
latter  group  has  been  metamorphosed  into  an  adamantine  pud- 
ding-stone, pebbles  of  which  are  profusely  scattered  among  the 
surrounding  drift.  The  sandstones  of  the  Dakota  have  also  been 
metamorphosed  into  hard  vitreous  quartzites.  Other  gneissic 
and  quartzitic  pebbles  in  the  drift,  showing  by  patches  of  quartz 
that  they  were  once  conglomerates,  appear  to  have  come  from 
some  obscure,  lower  and  metamorphosed  horizon  lying  between 
the  Trias  and  the  granite  and  may  be  of  ancient  Paleozoic  origin. 
The  uplifted  strata  of  the  , various  groups  offer  a most  picturesque 
appearance  from  South  Boulder  to  North  Boulder  canon.  Gigan- 
tic, massive  sheets  of  strata  are  uplifted  to  a height  of  some 
2,000  feet  above  the  valley,  and  carved  by  numerous  chasms,  into 
pinnacles  and  cathedral  spires.  The  heat  produced  by  the  fric- 
tion of  this  extreme  uplift  of  these  thick  masses  has  doubtless 
caused  the  partial  metamorphism  we  find  in  them.  On  the  back 


76 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


of  these  great  hog-backs,  occupying  an  humbler  position,  are 
the  marine  shales  of  the  Fox  Hills,  Cretaceous  and  Colorado 
group,  a thousand  or  more  feet  in  thickness.  These  are  simi- 
larly uplifted,  but  owing  to  their  softness  have  been  degraded  to 
a lower  level.  Above  them  in  order  follow  the  shaley  beds  and 
sandstones  of  the  Laramie  group.  These,  as  they  approach  the 
mountain  border,  partook  of  the  same  uplift,  but  the  whole  of 
the  uptilted  part  has  been  removed,  and  eroded  back,  till  the 
nearly  level  portion  which  underlies  the  prairie  has  been  left  in 
the  position  we  find  it,  forming  the  bluffs  and  flat  area  of  the 
Marshall  coal  field,  and  dipping  to  the  southeast  only  five 
degrees.  The  line  of  the  fault  passing  through  the  coal  fields, 
points  in  the  direction  of  the  deep  narrow  gash  in  the  mountains 
caused  by  South  Boulder  canon,  suggesting  a common  origin 
for  both  canon  and  fault,  along  one  line  of  fracture.  Remarkable 
terraces  of  drift  material  are  seen  resting  high  up  against  the 
flanks  of  the  mountains,  lying  unconformably  upon  the  tops  of 
the  various  upturned  strata.  These  appear  to  mark  the  level  of 
certain  great  lakes  that  at  one  time  covered  a large  area  of  this 
region.  The  different  levels  of  these  terraces  mark  the  gradual 
recession  and  pauses  of  the  waters  of  these  lakes  and  their  sub- 
sequent erosion  by  post-glacial  streams. 


CHAPTER  V. 


Canon  City  Area. 


Chapter  V. 

CANON  CITY  AREA. 

From  the  Denver  basin  going  southward  we  come  to  what 
we  may  designate  as  the  Canon  City  area,  embracing  that  section 
of  country  lying  between  the  Divide  on  the  north  and  the 
Arkansas  river  on  the  south,  and  between  the  Colorado  range  on 
the  west  and  an  indefinite  line  of  the  prairie  to  the  east;  in  this 
area  are  the  towns  of  Colorado  Springs,  Pueblo  and  Canon  City. 

GEOLOGY. 

The  geology  of  this  dsitrict  has  many  features  in  common 
with  the  Denver  basin.  The  sedimentary  strata  are  uplifted  to 
verticality  along  the  mountain  border;  the  lower  section  of  these 
is  formed  of  Paleozoic  rocks  of  the  Carboniferous  and  Silurian 
periods,  resting  directly  upon  the  granite ; the  upper  of  Mesozoic 
strata.  Near  the  northern  part  the  uplifted  beds  are  obscured  by 
being  overlaid  by  the  horizontal  Monument  creek  Tertiary  lake 
beds  to  a depth  of  about  1,000  feet,  but  south  of  this  the  erosion 
has  removed  these  beds  over  a wide  area  back  to  the  Austin 
bluffs,  some  miles  out  on  the  prairie  east  of  Colorado  Springs, 
and  exposed  the  underlying  strata,  so  that  from  Colorado  Springs 
along  the  road  to  Manitou  we  have  a grand  complete  section  of 
the  earth’s  crust  from  the  Tertiary  down  to  the  Archean  granite. 
The  uplifted  strata  are  well  seen  in  the  celebrated  Garden  of  the 
Gods  and  between  that  point  and  the  granite  back  of  Manitou. 
They  consist  of  Fox  hill  shales,  Colorado  limestone  with  its 
characteristic  Inocerami  shells,  Dakota  sandstone,  Gypsiferous 
Jurassic  limestone,  and  red  Triassic  conglomerate,  and  below 
these,  variegated  sandstones  and  limestones  of  the  Carboniferous, 
red  limestones  and  dark  reddish  brown  and  olive  green  sand- 
stones of  the  Silurian,  the  latter  forming  the  walls  of  the  Ute  and 
Williams  canons  at  Manitou,  until  finally  we  reach  the  Archean 
granite  and  gneiss  of  which  Pike’s  Peak  may  be  taken  as  a type. 


So 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


The  peculiar  vertical  and  overturned  dips  of  the  strata  may  be 
explained  on  the  “S”  fold  theory  we  have  already  discussed  at 
Golden.  The  Laramie  group  does  not  occur  prominently  in  this 
section,  but  about  ten  miles  east  of  Colorado  Springs,  either  by 
erosion  or  a fold,  it  is  brought  to  the  surface,  exposing  coal  seams 
which  have  been  worked  for  some  years  at  Franceville,  along  the 
line  of  the  Fort  Worth  railroad. 

OIL  WELLS. 

From  Colorado  Springs  south  we  enter  a wide  bay  in  the 
mountain  outline,  dividing  the  Colorado  from  the  Greenhorn 
range.  Through  the  centre  of  this  the  Arkansas  river  flows,  issuing 
from  its  canon  in  the  granite.  The  strata  in  this  bay  consist  of 
horizontal  table  lands  of  the  Colorado  and  Fox-hill  group.  In 
the  latter,  at  Florence,  oil  is  found  by  boring.  At  1,225  feet  the 
first  oil  sand  was  struck,  followed  by  an  explosion  of  gas.  The 
wells  have  been  continued  to  1,400  and  1,500  feet,  bringing  up, 
at  the  latter  depth,  water  90°  F.  The  location  of  the  wells  is 
about  the  center  of  the  basin,  which  is  formed  by  the  rocks  in 
the  vicinity  of  the  ranges  tipping  up  in  a semicircle  around  it  at 
an  angle  of  45  to  75  degrees.  The  geological  position  of  the  oil 
wells  is  shown  by  the  presence  of  a table  land  called  Castle 
Rock,  a short  distance  from  them,  which  is  capped  by  the 
“ fucoidal”  sandstone,  which  immediately  underlies  the  coal,  hence 
the  oil-sand  lies  about  1,500  feet  below  the  coal  in  the  Fox- hill 
shales, 

THE  COAL  FIELD. 

The  table  lands  and  bluffs  of  sandstone  on  the  south  side  of 
the  river,  between  Florence  and  Canon  City,  contain  the  Canon 
City  coal  field,  a basin  isolated  by  erosion  from  the  main  coal 
field  along  the  range.  It  is  an  irregular  oval,  about  twelve  miles 
long  by  two  miles  broad,  consisting  of  heavy  beds  of  sandstone, 
with  shales  and  coal  seams  resting  on  the  basal  “fucoidal” 
sandstone,  and  that  on  the  Fox-hill  shales.  The  coal  outcrops 
along  the  exposed  edges  of  the  field,  which  is  in  the  form  of  a 
synclinal  fold,  as  the  strata  are  tipped  up  toward  the  west  by  the 
range,  and  dip  in  toward  the  center  from  the  east,  involving  a 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


81 


second  anti-clinal  before  they  can  again  conform  to  the  hor- 
izontal strata  of  the  prairie.  This  is  one  of  those  secondary  rolls 
or  undulations  often  observed  along  the  flanks  of  the  mountains. 

The  coal-bearing  formation  is  about  700  feet  thick,  consisting 
of  sandstone  and  shales,  containing  several  small  coal  seams  of 
unworkable  size,  followed  below  by  one  from  three  to  five  feet 
thick,  developed  by  the  Colorado  Coal  and  Iron  Co.  and  the 
Santa  Fe  R.  R.  Co.  In  the  valley  of  Oak  Creek,  at  the  Santa 
Fe  mines,  we  descend  a shaft  300  feet  deep,  and  at  the  bottom 
find  the  seam  three  feet  wide  and  nearly  horizontal.  The  tunnels 
are  low  and  cramped  and  the  air  somewhat  warm  and  stifling. 
The  mine  is  developed  by  the  “ long  wall  ” system.  The 
pressure  of  the  heavy  sandstones  above  is  utilized  in  breaking 
down  the  coal,  which  cracks  off  with  a report  like  that  of  a 
pistol.  The  coal  gives  off  a good  deal  of  noxious  gas,  resulting 
sometime  since  in  a fatal  accident.  In  places  (where  it  is  safe  to 
do  so),  the  presence  of  gas  can  be  shown  by  applying  a naked 
lamp  to  the  crevices  whence  it  exudes,  when  it  ignites  with  a 
vivid  flash.  The  ventilation  is  by  fans  and  the  hoisting  is 
through  the  shaft.  In  digging  this  shaft  312  feet,  as  many  as 
nine  small  coal  seams  were  met  with  before  the  present  workable 
one  of  three  feet  was  encountered.  Although  the  seam  was  so 
narrow,  the  coal  is  of  sufficiently  good  quality  to  warrant  much 
labor  in  developing  it.  It  is  to  be  observed  that,  as  at  Golden, 
and  generally  along  the  foot-hills,  it  is  the  lowest  seam  in  the 
formation  that  is  workable. 

In  the  same  field  the  Colorado  Coal  and  Iron  Company  have 
for  many  years  been  working  their  mine  on  Coal  Creek,  a branch 
railway  line  running  from  Florence  to  the  mine  and  village.  As 
we  ascend  the  creek  we  notice  the  drab  shales  of  the  Fox-hills 
Cretaceous,  curiously  sculptured  by  rain,  and  revealing  their 
marine  origin  by  numerous  fossil  shells ; further  up,  the  shales 
are  capped  by  the  yellow  “fucoidal”  sandstone,  with  its  character- 
istic impressions  of  seaweed  (Halymenites)  showing  that  we  are 
approaching  the  limit  of  the  marine  formations,  and  soon,  above 
them,  we  find  evidences  of  land,  in  fossil  plants  and  leaves  of 
trees  imbedded  in  the  sandstone,  quickly  followed  by  a seam  of 
coal  5 feet  thick  dipping  westerly  into  the  hillside  at  an  angle  of 


82 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


5 degrees.  Down  this  dip  a slope  is  run  at  the  Coal  Creek  mine, 
from  which  tunnels  and  rooms  are  run  off  on  either  side.  The 
developments  extend  underground  over  a mile  in  length,  and 
half  a mile  in  breadth.  Four  feet  of  the  coal  is  worked,  and  the 
remaining  foot,  which  is  separated  by  a clay  seam,  is  left  to 
strengthen  the  roof.  The  holes  for  blasting  are  driven  by  hand- 
boring drills,  the  rest  of  the  work  is  by  pick  and  shovel.  Trans- 
portation is  by  mules  from  the  side  levels  to  the  incline,  when  a 
steam  engine,  with  wire  cable,  hauls  about  sixteen  cars  at  a time 
up  the  slope.  Ventilation  is  by  air  shaft  and  fan.  About  130 
men  are  employed  at  this  mine,  and  an  equal  number  on  Oak 
Creek. 

The  seam  is  free  from  slate  or  other  impurities.  The  coal  of 
this  area,  though  long  celebrated  through  the  State  for  its  excel- 
lent qualities  for  domestic  and  blacksmithing  purposes,  is  beyond 
the  coking  line,  which  we  find  restricted  to  the  Trinidad  region. 

Below  the  coal,  the  massive  “fucoidal”  sandstone  is  exten- 
sively quarried  for  building  stone. 

DINOSAUR  DISCOVERIES  AND  OIL  WELL  ON  OIL  CREEK. 

About  ten  miles  to  the  north  of  Canon  City  is  a small  park 
through  which  runs  Oil  Creek.  This  park  is  • celebrated  for  two 
things,  both  perhaps  having  some  obscure  relation  to  one 
another — the  discovery  of  oil  in  it  many  years  ago,  and  in  later 
years  of  enormous  saurian  remains,  similar  in  many  respects  to 
those  at  Morrison.  The  rocks  of  the  park  consist  principally 
of  red  Triassic  sandstones  overlaid  by  variegated  shales  and  clays 
of  the  Jurassic,  capped  by  the  Dakota  sandstone,  forming  a shal- 
low, synclinal  basin,  the  strata  in  the  centre  being  horizontal. 
These  have  been  cut  by  erosion  into  towers,  castle  rocks  and 
other  picturesque  forms,  a romantic  spot  suitable  for  sepulchers 
of  the  mighty  saurians  whose  bones  repose  there.  At  the  time 
of  our  visit  Professor  Marsh’s  party  were  excavating  the  skeleton 
of  a gigantic  dinosaur  from  the  solid  sandstone ; the  black  ends 
of  a huge  thigh  bone,  six  feet  long  and  proportionately  thick, 
were  protruding  from  the  rock,  while  a row  of  equally  huge  ver- 
tebra (part  of  the  animal’s  tail  that  had  been  exhumed)  were  lying 
on  the  bluff  ready  for  packing  up.  Quite  a number  of  different 


GEOLOGY  OF  COL  OF  A BO  COAL  FIELDS. 


83 


animals  of  the  saurian  family  have  been  obtained  from  the  locality 
by  Professors  Marsh  and  Cope.  Upon  these  Atlantosaurus  beds 
in  1862  a well  was  put  down  in  search  of  oil,  traces  of  which  had 
been  found  floating  as  an  iridescent  scum  upon  the  waters  of  the 
creek,  and  at  100  feet  several  barrels  were  obtained  of  a thick 
lubricating  oil,  of  a dark,  blackish  green  color,  42  degrees  Baume. 
Thus  it  appears  there  is  a Jurassic  oil  horizon  at  least  3,000  feet 
below  that  found  at  Florence  in  the  Cretaceous.  If  the  oil  reser- 
voir is  in  these  saurian  beds,  it  has  been  suggested  that  its  origin 
may  have  been  from  the  organic  portions  of  those  monsters,  pre- 
served as  hydrocarbons,  for  oil  is  admitted  to  result  from  distil- 
lation of  animal  and  vegetable  remains  such  as  are  found  fossil- 
ized in  the  rocks.  The  ultimate  source  of  this  oil,  and  perhaps 
even  that  at  Florence,  may  arise  from  a still  lower  horizon,  such 
as  that  of  the  Carboniferous  and  Silurian  limestones  which  out- 
crop on  the  edge  of  the  Grand  Canon.  The  oil  wells  in  the 
neighborhood  of  Canon  City  have  been  working  now  for  some 
years  with  fair  results  and  have  become  part  of  the  industries  of 
the  State.  Just  west  of  the  city  the  Colorado  limestone,  full  of 
large  inoceramus  shells,  is  extensively  quarried  by  the  convicts 
of  the  penitentiary.  At  the  base  of  the  Dakota  hogback,  back  of 
it,  a number  of  pleasant  tasting  carbonated  springs  issue.  At  the 
mouth  of  the  canon  between  the  Dakota  and  the  granite  are  hog- 
backs of  some  3,000  feet  of  Jurassic,  Triassic,  Carboniferous  and 
Silurian  sandstones  and  limestones  of  a reddish  color.  In  the 
Silurian  we  find  fragments  of  fossil  corals  and  shells;  at  its  junc- 
ture with  the  granite,  a hot  saline  spring  issues,  the  water  of 
which  is  90  degrees  F.,  and  contains  common  salt,  with  a per- 
centage of  carbonate  of  soda;  a bath  house  is  erected  over  the 
springs.  From  this  point  we  enter  the  Grand  Canon  of  the 
Arkansas,  cloven  by  water  2,000  feet  deep,  through  solid  granite, 
gneiss  and  hornblendic  rock. 


CHAPTER  VI. 


Trinidad,  or  Raton  Coal  Fields. 


MAP  OF  TRINIDAD  REGION, 
after  Hayden’s  Survey 


Jlower  coal  horizon. 


Chapter  VI. 

THE  TRINIDAD,  OR  RATON  COAL  FIELDS. 

After  leaving  the  Canon  City  district,  there  is  an  interval  of 
some  miles  between  the  Arkansas  and  Huerfano  Rivers,  in  which 
no  coal  of  importance  has  so  far  been  discovered.  A few  miles, 
however,  below  the  Huerfano  River,  is  one  of  the  largest  and 
most  important  coal  fields  east  of  the  Rocky  Mountain  range, 
covering,  not  only  a large  portion  of  Southeastern  Colorado,  but 
extending  for  many  hundreds  of  square  miles  into  New  Mexico, 
and  occupying  a large  part  of  the  Maxwell  Grant.  We  call  this 
the  Trinidad  Coal  Fields,  from  the  name  of  that  important  city 
located  upon  it,  in  the  extreme  southern  limit  of  the  State. 
The  table-lands  which  contain  the  coal,  belong,  properly,  to  what 
are  called  the  Raton  Mountains,  the  field  being  by  some  called 
the  Raton  Coal  Field.  The  town  of  Raton  is  situated  on  the 
field,  south  of  the  Colorado  Line,  in  New  Mexico. 

The  area  occupied  by  this  great  field  is  about  750  square 
miles,  including  the  portions  both  in  Colorado  and  New  Mexico, 
extending  on  the  north  from  the  Huerfano  River,  in  Colorado, 
to  the  Cimarron  River,  in  New  Mexico.  It  is  bounded  on  the  west 
by  the  Sangre  de  Christo  range,  and  on  the  east  by  the  erosion 
of  the  prairie,  in  a line  approximately  corresponding  with  that  of 
the  Rio  Grande  and  Fort  Worth  Railways. 

TOPOGRAPHICAL  AND  GEOLOGICAL  FEATURES. 

The  main  feature  of  this  region  is  a long,  wide  plateau,  of  a 
very  uniform  appearance  and  structure,  running  for  many  miles 
along  the  flanks  of  the  mountain  ranges  and  extending  out  on  to 
the  prairie  border,  where  it  is  abruptly  cut  off,  showing  for  many 
miles  a steep,  monotonous  wall  of  yellow  sandstone,  underlaid  by 
dark  gray  shales,  about  300  to  500  feet  high,  indented  here  and 
there  by  sharp  ravines,  from  which  small  streams  issue,  till  we  reach 
the  Purgatoire  River,  upon  whose  banks  the  town  of  Trinidad 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


is  situated.  The  plateaus  then  assume  a much  loftier  aspect, 
forming  a table-land,  called  the  Chicorica  mesa,  2,000  feet  high 
above  the  river  bed.  The  top  of  the  mesa  is  capped  by  basaltic 
lava,  which  has  preserved  the  full  thickness  of  the  Laramie  coal- 
bearing group,  part  of  which  has  been  removed  by  erosion  from 
the  greater  portion  of  the  rest  of  the  field. 

A section  of  this  plateau  shows  three  important  divisions : 

(1st.)  At  the  base  is  an  unknown,  but  probably  great  thick- 
ness of  the  marine  Cretaceous  shales  of  the  Fox-hills  Group,  of 
a drab  gray  color,  containing  many  marine  fossil  shells  and  con- 
cretions of  clay  ironstones. 

(2d.)  These  are  capped  by  the  yellow  fucoidal  sandstone, 
which  in  this  region  is  very  conspicuous  from  its  massive  char- 
acter, forming  a distinct  line  of  yellow  rock  from  50  to  100  feet 
thick,  traceable  all  over  the  region,  and  marking  off  the  down- 
ward limit  of  the  coal-bearing  series  which  lies  immediately 
above  it,  from  the  non  coal-bearing  shales  which  lie  below  it. 
The  seaweed  impressions  (halymenites)  are  very  common  and 
distinct,  and  the  sandstone  is  extensively  quarried  for  building 
stone  and  grindstones,  for  which  purpose  it  is  one  of  the  best  in 
the  state. 

(3d.)  Between  50  and  100  feet  above  this,  the  coal  seams  of 
the  Laramie  group  commence.  The  first  seam  is  usually  from 
two  to  four  feet  thick,  and  not  generally  worked  in  Colorado.  A 
few  feet  above  this  is  the  main  or  Trinidad  seam  from  six  to 
fourteen  feet  thick,  and  the  one  generally  worked.  Numerous 
small  seams  and  indications  of  coal,  with  intervals  of  sandstone 
and  shale  between  them,  occur  to  the  top  of  the  mountain,  and 
about  800  feet  above  the  lower  seams,  a cluster  of  small  seams 
occur  which  are  in  some  places  of  workable  thickness.  Through- 
out the  entire  Laramie  group  of  1,800  feet  thickness,  fossil- 
plants  and  thin  seams  of  lignite  are  common.  Wheeler’s  survey 
counts  about  32  seams  of  coal,  both  small  and  great,  in  this 
mesa,  making  about  105  feet  of  coal  altogether,  not  more  than 
20  feet  on  an  average  being  workable.  Prof,  van  Diest  estimates 
the  amount  of  workable  coal  contained  in  the  entire  field  at 
10,000,000,000  tons. 

The  lower  and  main  seams  appear  to  be  pretty  constant  over 
the  greater  part  of  the  field,  though  varying  from  place  to  place 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


89 


in  thickness  and  quality.  In  fact,  this  variability  is  a notable 
feature  of  this,  as  well  as  of  other  large  coal  fields.  Thus,  at 
Engleville  the  Trinidad  seam  is  twelve  feet  thick.  Five  miles 
southwest  of  it,  at  Starkville,  it  is  only  six  feet ; and  eight  miles 
east,  at  Gray  Creek,  it  is  eight  feet,  and  is  in  places  split  up  by 
partings  into  several  seams.  Over  the  border,  in  New  Mexico, 
the  Trinidad  bed  is  only  five  feet,  occurring  locally  on  Crow 
Creek,  and  is  very  shaly,  while  the  Dillon  bed,  which  lies  below 
the  Trinidad,  and  in  Colorado  is  seldom  of  workable  size,  is 
there  five  feet,  and  extends  over  much  of  that  region.  Professor 
Van  Diest  enumerates  twelve  coal  beds  in  New  Mexico,  varying 
from  three  to  five  feet,  aggregating  forty-five  feet  of  coal,  and 
remarks  “that  all  these  beds  do  not  extend  over  the  whole  of 
the  Maxwell  Grant,  the  lowest  beds,  as  in  Colorado,  having  the 
greatest  extent,  the  higher  beds  being  much  limited  by  erosion.” 
The  thickest  and  probably  central  portion  of  the  coal  fields 
seems  to  lie  under  Fisher’s  Peak. 

The  coal  field  was  once  of  far  greater  proportions  than  at 
present,  having  been  limited  especially  to  the  east  by  extensive 
erosion.  It  was  doubtless  connected  with  the  Canon  field  to  the 
north,  as  that  was  once  with  the  fields  of  Northern  Colorado, 
and  those  again  with  the  Laramie  fields  of  Wyoming.  To  the 
south,  also,  below  the  Maxwell  Grant,  it  had  doubtless  a much 
larger  extent. 

The  coal  plateau  is  not  a flat  table  land,  but  a shallow  trough, 
one  side  of  which  tips  up  at  a steep  angle  toward  the  west,  in 
the  neighborhood  of  the  Spanish  peaks  and  the  main  range,  by 
the  elevation  of  those  mountains,  and  at  a gentler  angle  in  an 
opposite  direction  toward  the  east,  where  it  is  cut  off  by  erosion. 
The  river  Purgatoire  occupies,  approximately,  the  center  of  the 
trough  so  formed.  In  the  New  Mexico  region  the  same  folding  is 
observable,  and  it  was  this  folding  which  has  brought  the  coal  above 
the  surface  within  easy  reach  of  development  by  tunnels  without 
the  need  of  deep  shafts.  Besides  these  principal  folds,  several 
minor  inductions  of  the  strata  occur  locally. 

VOLCANIC  ROCKS. 

Another  striking  feature  of  this  region  is  the  presence  of  vol- 
canic rocks,  erupted  through  the  coal  plateau.  The  plateaus  are 


9o 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


penetrated  by  a network  of  lava  dykes,  and  in  some  cases,  as  at 
Fisher’s  Peak,  part  of  the  flow  that  issued  from  these  dykes  still 
remains  and  protects  the  coal  series  over  a large  area  from  ero- 
sion. In  other  cases  the  lava-cap  has  been  removed,  and  nothing 
but  the  dykes  or  channel  sources  remain.  One  of  the  “foci”  of 
these  eruptions,  which  occurred,  probably,  in  tertiary  times,  long 
after  the  coal  strata  were  deposited,  is  in  the  neighborhood  of  the 
Spanish  Peaks  and  adjacent  (La  Veta,  Sheep  and  Silver)  moun- 
tains, near  the  northwestern  portion  of  the  district.  From  these 
great  “laccolites”  or  subterranean  reservoirs  of  volcanic  rock, 
an  immense  number  of  dykes  radiate  for  miles  over  the  adjacent 
country.  The  influence  of  the  heat  from  these  volcanic  outbursts 
has  been  felt  by  the  coal,  large  areas  of  which  have  been  changed 
from  the  lignite  of  the  north  into  a fine  bituminous,  and  also  into 
a good  coking  coal,  and  locally,  in  close  proximity  to  some  of 
the  dykes,  where  the  heat  was  greatest,  into  a natural  coke,  or 
even  into  an  impure  graphite.  The  coking  coal  area  appears  to 
to  be  limited  in  Colorado  to  the  southern  portion  of  the  field, 
from  the  Purgatoire  River  to  the.Chicosa;  the  coal  north  of  that, 
though  caking,  will  not  coke. 

Near  the  northern  portion  of  the  area,  between  the  Huerfano 
River  and  the  Spanish  peaks,  Mr.  R.  C.  Hills  has  discovered 
extensive  tertiary  lake-beds  of  great  thickness,  that  originally 
covered  a large  portion  of  the  Laramie  coal  plateau,  and  lie 
unconformably  with  the  dip  of  the  latter.  In  the  sandstones  and 
shales  some  fossil  turtles  and  other  remains  of  Tertiary  origin 
were  found.  The  dykes  and  laccolites  of  the  Spanish  peaks 
are  surrounded  by  a great  thickness  of  this  formation.  The  rest 
of  the  geology  and  stratification  of  the  region  is  similar  in  many 
respects  to  that  already  described  further  north  from  the  Creta- 
ceous to  the  Carboniferous,  which  latter  period,  according  to  Dr. 
Endlich,  rests  directly  upon  the  Archean  granite,  and  with  the 
other  upturned  Mesozoic  strata,  forms  the  flanks  of  the  Sangre 
de  Cristo  range,  to  the  west  of  the  coal  plateau. 

The  Trinidad  region  embraces  the  Walsenburg  district  on  the 
north,  including  the  Walsenburg,  Pictou  and  Rouse  mines.  The 
Santa  Clara  mines  are  a few  miles  further  south,  and  next  to 
them  are  the  Chicosa  mines,  including  the  Victor  and  Forbes 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


9* 


mines,  about  fifteen  miles  from  Trinidad;  lastly,  the  mines 
around  the  base  of  Fisher’s  Peak  in  the  neighborhood  of  Trin- 
idad. These  are  the  Gray  Creek  mines,  the  El  Moro  mines  at 
Engleville  close  to  the  city,  the  Trinidad  mines  at  Starkville,  six 
miles  further  to  the  south,  and  the  Sopris  mines  about  five  miles 
southwest,  near  the  river,  besides  all  which  there  are  several 
small  mines  opened  by  private  parties.  Just  over  the  Colorado 
border  are  the  Raton  coal  mines,  tributary  both  to  Colorado  and 
New  Mexico. 

EL  MORO  MINES  AT  ENGLEVILLE,  C.  C.  & I.  CO. 

These  mines,  located  at  the  base  of  Ushers  Peak,  about  four 
miles  southeast  of  Trinidad,  have  been  in  successful  operation  for 
upwards  of  twelve  years,  and  during  that  time  have  mined  out 
some  square  miles  of  coal,  and  their  developments  are  to  be  reck- 
oned by  miles  in  length  rather  than  by  feet,  as  in  the  younger 
mines.  There  are  thirteen  miles  of  track  now  in  this  mine,  a 
sketch  of  which  may  be  seen  in  Plate  VIII. 

The  developments  are  by  parallell  drifts,  one  of  which  is  6,600 
feet  long,  run  into  the  base  of  the  mountain,  and  working  to  the 
raise  on  the  gentle  dip  of  the  nearly  horizontal  strata,  so  that  the 
laden  cars  descend  easily  to  the  openings.  The  mine  is  devel- 
oped by  the  room  and  pillar  system.  From  the  main  entries 
double  entries  are  run  off  at  right  angles,  and  rooms  20  by  300 
feet  branch  off  from  these.  The  rooms  work  on  the  “face”  ol 
the  coal,  the  main  entries  being  driven  on  the  “butts.”  After 
the  rooms  are  worked  out  the  coal  pillars  are  cautiously  removed 
and  the  roof  allowed  to  cave  in.  As  the  seam  is  very  thick, 
being  from  nine  to  twelve  feet,  from  two  to  four  feet  of  coal  is  left 
in  the  roof,  which  is  much  safer  and  stronger  than  the  ordinary 
shale  or  sandstone,  so  fertile  in  accidents ; little  timber  is  con- 
sequently needed  in  the  mine.  A few  “rolls”  occur  here  and 
there,  pinching  the  coal  slightly,  also  some  “ nigger  heads  ” or 
concretions  of  shale  or  iron  pyrites  are  met  with  occasionally, 
and  a few  thin  partings  of  bone  or  shale  at  irregular  intervals, 
near  the  top,  middle  or  bottom  of  the  seam.  It  is  these  clay 
partings  which  cannot  be  separated  from  the  coal,  that  give  the 
rather  high  per  cent,  of  “ ash  ” in  the  analysis  of  the  coke. 


92 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


It  will  be  observed  that  all  these  mines  are  opened  only 
within  easy  access,  or  directly  along  the  lines  of  the  railroad 
routes,  the  centre  of  the  plateau  and  the  western  upturned  por- 
tion being  at  present  undeveloped,  though  doubtless  some  of  it 
has  been  taken  up  by  speculators. 

Government  sells  coal  land  at  $ 20  per  acre  when  within 
fifteen  miles  of  the  railroad,  and  at  $10  per  acre  outside  of  those 
limits,  and  as  one  individual  can  take  up  but  160  acres,  it  is  nec- 
essary for  a company  wishing  to  acquire  a large  tract  to  buy  out 
several  individual  claimants. 

About  one-half  of  the  coal,  including  slack  and  screenings,  is 
turned  into  coke  at  El  Moro  and  shipped  to  the  Bessemer  works 
at  Pueblo,  and  to  the  various  smelting  establishments  along  the 
line  of  the  Rio  Grande  Railroad. 

The  ventilation  of  the  mine,  owing  to  the  large  size  and 
roominess  of  the  developments,  is  very  good,  and  is  increased  by 
furnaces  built  at  the  ends  of  some  of  the  entries. 

The  “ face  and  end”  or  “butt”  cleavage  of  the  coal  is  very 
marked,  and  is  a great  assistance  in  breaking  the  coal  down. 
The  Lechner  coal-cutting  machines  are  used,  worked  by  a 
Norwalk  steam  air  compressor.  The  coal  cutter  cuts  a hori- 
zontal distance  of  five  feet  at  the  base  of  the  seam,  each  foot  rep- 
resenting a ton  of  coal.  After  the  undercutting,  the  coal  is  blasted 
down  by  powder  and  broken  up  by  picks ; one  machine  will  cut 
1 50  tons  per  day. 

During  the  first  seven  years  the  production  was  about  300,000 
tons  per  annum.  In  1885  it  was  96,592  tons  of  coke  and  265,000 
tons  of  coal.  In  1888  it  was  300,382  tons,  since  which  time  the 
production  has  largely  increased.  The  cost  of  production  was 
said  to  be  about  73  cents  per  ton  in  1885,  and  coal  was  sold  at 
the  pit  mouth  at  $1.00  per  ton. 

The  coal  is  bituminous  having  a brilliant  lustre,  breaking  in 
large,  firm  blocks,  which  slack  but  little  from  exposure. 

This  is  one  of  the  leading  and  older  mines  in  Colorado,  and 
from  its  dryness,  roominess  and  perfect  development,  may  be 
called  an  ideal  coal  mine.  Perhaps  the  only  deficiency  is  a lack 
of  water  which  has  to  be  brought  in  barrels  from  the  Purgatoire 
river  at  El  Moro,  six  miles  distant,  where  a plant  of  two  or  three 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


93 


hundred  coke  ovens  is  in  active  operation,  the  water  being 
pumped  up  to  them  by  steam  power  from  the  river. 

THE  TRINIDAD  COAL  AND  COKE  COMPANY’S  MIMES  AT  STARKVILLE. 

Leaving  Trinidad  we  skirt  the  broad  base  of  Fisher’s  Peak 
for  about  six  miles  along  the  south  bank  of  the  Purgatoire  river, 
passing  on  the  road  several  undeveloped  exposures  of  two  or 
three  seams  of  coal.  The  scenery  is  picturesque.  To  the  south- 
west the  coal  plateau  stretches  away  to  the  Sangre  de  Cristo 
range,  whose  blue  serrated  outlines  cut  the  horizon  about  thirty 
miles  away.  To  the  northwest  the  Spanish  Peaks  rise  like  gray 
pyramids  above  the  plateau.  To  the  east  the  coal  plateau  is 
seen  to  be  abruptly  cut  off,  and  faces  with  its  yellow  wall  the 
great  plains,  and  on  either  bank  of  the  stream  the  same  plateau 
rises  with  its  ashen-gray  slope  covered  with  pinons,  the  top 
capped  with  a characteristic  belt  of  sandstone.  A tributary  of 
the  Purgatoire,  called  Raton  Creek,  heads  up  to  the  south  in  the 
Raton  pass,  a gap  which  forms  the  gate-way  through  the  Raton 
mountains  to  New  Mexico,  and  is  occupied  by  the  track  of  the 
Santa  Fe  Railroad.  We  follow  up  this  creek  in  the  direction  of 
Starkville.  Along  the  road,  within  a mile  of  the  village,  we 
cross  two  small  dykes  of  basalt,  heading  up  towards  Fisher’s 
Peak,  and  passing  directly  through  the  coal-seams.  These  are 
some  of  the  many  dykes  of  lava  which  intersect  this  region,  and 
which  for  the  most  part  seem  to  have  come  up  through  one  of 
the  northwest  and  southeast  cleavage  cracks,  which  have  cut  up 
this  entire  region  like  a checker  board.  Their  eruption  appears 
to  have  little  disturbed  the  adjacent  strata,  beyond  baking  it  for 
a short  distance,  and  sometimes  producing  a fine  cleavage  struc- 
ture near  the  dykes.  Most  of  these  dykes  besides  emanating 
under  Fisher’s  Peak,  and  being  doubtless  the  immediate  source 
of  its  lava  cap,  have  a converging  direction,  pointing  towards  the 
Spanish  peaks,  thirty  miles  distant.  These  peaks  are  a center  of 
eruption,  and  are  formed  by  a concentration  of  an  immense  num- 
ber of  dykes  issuing  from  one  or  more  large  laccolites  as  if  the 
region  had  been  violently  fractured  at  this  point,  from  which  as  a 
“ focus,”  a multitude  of  minor  fractures  and  fissures  shattered  the 
surrounding  country,  through  which  welled  up  the  molten  lava, 


94 


GEOLOGY  OF  COLORADO  COAL  FIELDS 


pouring  a flood  over  the  coal  plateau,  part  of  which  still  remains, 
capping  Fisher’s  Peak,  and  portions  of  the  Raton  mountains, 
and  preserving  the  coal  strata  in  the  position  we  find  them.  The 
heat  from  these  dykes  and  overflows  probably  had  the  effect  of 
partially  debituminizing  the  surrounding  coal,  producing  that 
coking  quality  which  distinguishes  it  from  other  unaltered  coals 
in  the  State.  It  is  worthy  of  note  that  the  districts  in  Colorado 
(Trinidad,  Crested  Butte  and  Glenwood),  which  produce  the 
coking  coals,  are  those  where  volcanic  agencies  have  been  spec- 
ially active.  At  Trinidad  local  deposits  of  graphite  are  found? 
and  a little  south  in  New  Mexico,  anthracite,  both  in  connection 
with  dykes  of  lava,  while  at  Crested  Butte  anthracite  occurs, 
where  the  lava  and  eruptive  agencies  are  most  conspicuous. 
Anthracite  and  graphite  are  well  known  to  be  common  coal 
metamorphosed  by  heat,  and  the  coking  condition  appears  to  arise 
from  the  same  cause  more  gently  applied. 

The  little  village  of  Starkville,  numbering  about  500  inhabi- 
tants, is  situated  on  the  banks  of  Raton  Creek,  in  close  proximity 
to  the  mine  at  the  base  of  Fisher’s  Peak.  The  creek  has  exposed 
many  natural  sections  of  the  coal  strata  and  coal  beds  along  its 
course.  In  one  place  the  yellow  massive  sandstone  forms  the 
bed  of  the  creek ; upon  this  rests  from  50  to  100  feet  of  shale, 
with  a thin  seam  of  coal  two  feet  thick  in  the  lower  portion,  and 
above  it  a thicker  seam  five  to  seven  feet;  the  latter  seam  is  the 
one  worked.  Higher  up  the  creek,  near  Wooten’s  ranch,  the 
same  section  and  the  same  coal  seam  appears.  Over  the  Raton 
pass,  and  on  the  south  slope  of  Fisher’s  Peak,  are  the  Raton 
mines,  upon  which  considerable  development  has  been  done. 
These  mines  are  also  on  the  Santa  Fe  Railroad  line. 

The  mines  at  Starkville  are  very  similar  in  character  and 
system  of  development  to  those  at  Engleville.  The  coal  seam  is 
not  so  thick,  being  six  or  seven  feet,  and  so  does  not  admit  of 
leaving  coal  on  the  roof,  hence  the  shale  and  sandstone  require 
much  more  timbering  for  their  support.  The  coal  shows  dis- 
tinct lines  of  stratification  and  bedding,  each  layer  of  coal  being 
about  one  foot  thick;  sometimes  a little  shale  exists  between  the 
beds.  The  dip  of  the  coal  is  to  the  southwest,  rising  three 
degrees  to  the  east,  with  occasionally  a rise  or  fall  toward  the 
north,  caused  locally  by  a few  gentle  “ rolls.” 


ENGLEVILLE  COAL  MINES  NEAR  TRINIDAI)  COLO. 

COLORADO  COAL  & IRON  CO. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


95 


The  mine  is  practically  level,  the  general  outward  dip  to  the 
outlets  gives  an  excellent  down  grade  for  the  laden  cars.  Some 
seams  of  fire-clay  occur  above  the  coal,  said  to  make  good  lining 
brick  for  the  ovens,  also  a belt  of  concretionary  iron  ore,  which 
is  found  at  several  points  around  the  mountain.  The  tendency 
of  coal  seams  to  break  up  into  two  or  more  seams  by  shale 
partings,  and  after  awhile  to  come  together  again,  is  observable 
at  this  side  of  the  mountain  also.  At  both  Engleville  and  Stark- 
ville,  the  lack  of  a copious  supply  *of  water  situated  conveniently 
to  the  mines  is  much  felt,  especially  for  the  thirsty  coke  ovens. 
At  Starkville  this  is  remedied  by  bringing  it  in  pipes  from  a 
spring  five  miles  distant  and  high  up  on  the  mountains. 

There  are  some  eight  principal  entries,  old  and  new,  and  the 
mine  is  developed  on  the  same  system  as  that  at  Engleville. 
The  natural  surface  of  the  mountain  being  cut  by  little  ravines, 
several  cross  entries  to  daylight  have  been  driven,  which  con- 
tribute largely  to  ventilation.  The  coal  is  mined  by  pick  and 
shovel,  and  by  Harrison  coal-cutters,  worked  by  an  air  com- 
presser  with  seventy  horse-power  engine. 

A few  rods  from  the  mine  is  a long  line  of  bee-hive  coke 
ovens,  built  of  sandstone  and  lined  with  Milwaukee  fire-brick. 
The  screenings  are  run  direct  from  the  shutes  to  the  ovens  along 
a tramway  on  top  of  the  ovens.  The  rest  of  the  coal  is  dis- 
charged from  the  top  of  a lofty  trestle  tramway  connected  with 
the  main  entries,  into  the  cars  of  the  Santa  Fe  Railroad.  If  the 
surface  of  the  mountain  of  Fisher’s  Peak  were  removed,  four 
little  underground  cities  would  be  exposed,  with  their  streets, 
alleys  and  blocks  covering  several  square  miles.  This  would 
give  the  stranger  an  idea  of  what  has  been  worked  out  at  Engle- 
ville, Starkville,  Raton  and  Sopris,  and  the  extent  of  these  mines. 

A general  view  of  Starkville  and  its  vicinity  is  given  in  Plate 
VIII. 

SOPRIS  MINE.  (DENVER  FUEL  COMPANY.) 

This  mine  is  located  four  miles  southwest  of  Trinidad,  be- 
tween the  Purgatoire  river  and  the  base  of  Fisher’s  Peak,  not  far 
from  the  Starkville  mines,  its  seams  belonging  to  the  same 
system,  and  its  geology  being  similar  to  that  already  described. 


96 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


The  openings  are  up  a ravine  in  the  mesa  1,800  feet  from  the 
track  of  the  Fort  Worth  Railroad,  and  from  the  coke  ovens  and 
village  of  the  company,  located  on  the  flat  near  the  river.  (See 
Plate  VII.) 

The  coal  is  brought  from  the  mines  to  the  railway  and  coke 
ovens  by  a long  wire-rope  tramway,  worked  by  a fifty  horse- 
power engine.  The  dip  of  the  strata  inclosing  the  coal  is  about 
three  degrees  to  the  southwest.  There  are  two  coal  seams,  an  upper 
one  six  and  a-half  feet  thick,  and  a lower  one  forty  feet  below  it, 
four  feet  thick,  both  of  very  pure  coal,  with  little  admixture  of 
clay  partings.  The  latter  occasionally  occur  in  an  unusual  posi- 
tion, filling  joint  cracks  in  the  strata,  at  right  angles  to  the  bed- 
ding, and  at  intervals  of  from  50  to  200  feet.  A few  “rolls” 
also  occur,  as  is  usual  in  most  mines. 

The  main  entry  is  1,289  feet  l°ng,  and  from  six  to  eight  feet 
high ; the  coal  is  hauled  to  the  entrance  of  the  mine  by  mules, 
thence  to  the  tipple  by  tramway.  There  are  upwards  of  14,957 
feet  of  development  in  this  mine,  which  is  a large  showing  for 
the  few  months  that  it  has  been  opened.  Air  is  supplied  by  a 
fan  and  passes  through  the  mine  in  a chamber  running  parallel 
with  the  main  entry  for  1,260  feet.  The  number  of  men  em- 
ployed is  450,  of  whom  350  are  coal  miners.  The  latter  receive 
fifty  cents  per  ton,  the  rest  of  the  men  being  paid  by  the  day. 
The  daily  output  is  about  1,200  tons.  If  “dead  work,”  such  as 
cross-cut  through  barren  rock  has  to  be  done,  it  is  paid  by  the 
job.  Water  for  the  mine  is  pumped  up  from  the  river  about  a 
mile  distant,  and  stored  in  a reservoir  above  the  mine.  The  coal  is 
shoveled  on  to  the  railroad  cars  of  the  Fort  Worth  Railroad  by  the 
Ramsay  steam  coal  distributor.  All  the  most  modern  appliances 
of  steam  machinery  are  brought  to  bear,  and  the  advantages  of 
these  improved  time-saving  methods  are  shown  in  the  rapid 
development  and  large  output  of  this  young  mine.  Coal  is 
shipped  by  the  Fort  Worth  and  Rio  Grande  Railroads,  the  mar- 
kets being  along  their  line,  and  also  in  Nebraska  along  the 
Burlington  Route. 

A plant  of  100  coke  ovens  has  been  built  at  a cost  of  $100,- 
000.  The  return  for  coke  from  the  ovens  is  about  66  per  cent, 
or  175  tons  daily.  The  ovens  are  circular,  of  the  bee-hive  pattern, 


MINE  COLORADO  FUEL  COMPANY. 


GRAY  OREEK  CO.  MINES  & PROPERTY. 


VICTOR  MINE,  NEAR  CHICOSA  (VICTOR  COMPANY.) 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


97 


with  a diameter  of  twelve  feet.  The  coke  is  made  from  the 
slack  and  small  coal.  Twenty  men  are  employed  in  connection 
with  the  ovens,  and  are  paid  at  the  rate  of  $3.00  per  day.  Mar- 
kets for  the  coke  are  at  Omaha,  and  the  Grant  and  other 
smelting  works. 

Analysis  of  the  Sopris  coal  by  Prof.  George  C.  Tilden  : 


Water  

Volatile  matter 

• • • • 3318 

Fixed  carbon 

. . . . 57.56 

Ash  (brownish  gray)  . . . 

. . . . 8.65 

100.00 

Sulphur . . 

. . . . 0.751 

GRAY  CREEK  MINES. 

See  Plate  VII. 

These  mines  are  located  at  the  base  of  Fisher’s  Peak,  about 
six  miles  east  of  Trinidad.  The  openings  are  along  the  small 
ravines  tributary  to  Gray  Creek,  a little  stream  issuing  from  the 
Peak  and  flowing  into  the  Purgatoire  River.  It  has  a good 
supply  of  water  all  the  year. 

TOPOGRAPHY. 

The  flanks  of  the  Raton  table  land  in  this  vicinity  consist  of 
rolling  hills  and  benches  divided  by  narrow  but  not  very  deep 
ravines,  with  here  and  there  an  intervening  flat  meadow.  One  of 
these  meadows  forming  the  bank  of  Gray  Creek  has  been  chosen 
for  the  coal  village  of  Danforth,  numbering  some  thirty  new 
frame  houses,  and  adapted  from  its  proximity  to  water,  for  the 
location  of  coke  ovens  and  other  works  in  the  future. 

Up  one  of  the  ravines  a side-track  runs  to  the  mines,  and  a 
locomotive  transports  the  laden  cars  from  the  mouth  of  the  mine 
to  the  main  line  of  the  Fort  Worth  Railroad  at  Beshoar  station, 
about  a mile  distant.  There  the  coal  is  dumped  from  a tipple 
direct  into  the  cars. 


98 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


COAL  SEAMS. 

There  are  several  seams  on  this  property,  some  of  them  ot 
workable  size  at  a higher  horizon  than  is  common  in  this  table 
land.  The  lower  seams  correspond  to  those  worked  at  Engle- 
ville,  Starkville  and  Sopris.  There  are  also  several  localities  on 
the  property  where  the  seams  outcrop,  and  where  in  the  future 
some  of  them  could  be  conveniently  worked. 

Resting  upon  the  massive  “ basal  ” sandstone  is  a seam  about 
one  foot  in  width,  above  this  is  a second  seam  and  the  one  at 
present  developed,  from  six  to  eight  feet  thick,  which  appears  to 
be  the  continuation  eastward  of  the  main  Engleville  seam.  About 
fifteen  to  twenty  feet  above  this  is  a third  seam  of  clean  looking 
coal  four  feet  thick. 

Between  200  and  300  feet  above  these  lower  seams,  is  the 
upper  series  as  shown  on  the  section,  Plate  X,  in  which,  on  this 
property  one  seam  attains  six  feet  in  thickness.  In  proximity  to 
it  is  a bed  of  kidney  iron  ore  of  considerable  thickness.  Some  of 
the  lower  seams  at  different  localities  are  divided  into  several 
unworkable  smaller  seams  by  thick  belts  of  shale.  At  one  spot 
an  intrusive  sheet  of  basalt  has  entered  the  coal  seam,  and  reduced 
it  at  contact  to  an  impure  graphite  of  about  two  feet  in  thickness. 
Dykes  of  basalt,  doubtless  once  feeders  to  the  main  sheet  of  lava 
which  caps  the  table  land,  are  found  here  and  there,  and  in  one 
instance  the  development  of  a good  coal  seam  would  probably  be 
cut  off  by  one  of  these  basaltic  walls. 

The  seam  at  present  worked,  outcrops  in  plain  view  along 
the  flank  of  the  ravine,  showing  between  six  and  eight  feet  of 
coal.  Towards  the  center  of  this  seam  occurs  a somewhat  thick 
parting  of  shale  about  three  feet  six  inches  from  the  bottom,  and 
varying  from  two  feet  to  six  inches  in  thickness,  maintaining  its 
course  throughout  the  present  workings.  Near  the  bottom  of 
the  seam  a thin  parting  of  bone  about  one  inch  thick  also  occurs. 
These  partings  are  an  obstruction  to  the  clean  development  of 
the  coal  and  involve  a good  deal  of  extra  labor.  The  miners 
have  to  cut  18  inches  into  the  coal  below  the  shale,  remove  the 
coal,  then  break  down  the  shale  parting,  remove  it  separately, 
and  lastly  the  upper  two  feet  of  coal  is  taken  down  leaving  about 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


99 


one  foot  of  coal  to  support  the  roof.  It  is  difficult  to  keep  this 
shale  and  the  seam  of  bone  from  mixing  with  the  coal  which 
would  injure  the  coke  by  giving  a high  per  cent,  of  ash.  The 
coal  is  shipped  and  the  small  coal  is  sent  direct  to  El  Moro  for 
coking. 

The  average  dip  of  the  coal  seam  is  seven  degrees  and  to  the 
north.  Towards  the  northwestern  portion  of  the  workings  the 
dip  increases  to  eight  degrees,  involving  a steep  up  grade  from 
the  side  entries  and  rooms  towards  the  main  entry,  for  the  laden 
cars,  which  are  drawn  by  mules.  The  cause  of  this  steepness  of 
dip  is  said  to  be  the  presence  of  a dyke  of  basalt  about  500  feet 
to  the  northwest  running  parallel  with  the  two  main  entries. 

Several  rolls  occur  in  the  mine,  one  large  one  in  the  main 
entry  reduced  the  thickness  of  the  coal  considerably  for  a space, 
until  it  was  cut  through  and  the  coal  resumed  its  average  size. 

The  mine  is  developed  by  two  nearly  parallel  main  entries 
which  unite  at  the  main  outlet,  from  which  side  entries  and 
rooms  have  been  excavated. 

The  mine  has  been  running  about  eight  months  and  about 
6,000  feet  of  development  have  been  accomplished.  The  daily 
output  has  averaged  about  350  tons.  About  200  men  have  been 
employed.  The  work  is  by  pick  and  shovel.  Ventilation  is  at 
present  by  a furnace,  but  ere  long  a fan  will  be  necessary.  The 
Fort  Worth  and  Rio  Grande  railways  receive  the  coal  and 
distribute  it  at  various  points  along  their  routes. 

The  mine  is  owned  by  the  Gray  Creek  Company,  of  which 
Mr.  Delos  Chappel  is  manager. 


VICTOR  mine. 

See  plate  VII. 

This  mine  is  located  in  the  coal  plateau  sixteen  miles  north 
of  Trinidad  and  four  miles  west  of  the  Rio  Grande  railroad  track. 
The  works  are  situated  about  a mile  up  a ravine  called  the  Canon 
de  Agua  or  water  canon,  from  the  prevalence  of  springs  near  the 
head  of  the  ravine.  The  next  canon  to  the  south  is  the  Chicosa, 


IOO 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


up  which  runs  a branch  line  from  the  Denver  & Rio  Grande  main 
track  to  the  Chicosa  coal  mines,  worked  by  the  Forbes  Company. 
The  side  track  from  the  Victor  mine  unites  with  this  Chicosa  line 
and  both  discharge  their  coal  at  Chicosa  station  on  the  main  line. 
On  approaching  the  great  plateau  from  the  open  prairie  we  see 
before  us  an  abrupt  line  of  cliffs  capped  at  the  top  by  the  basal 
sandstone,  from  which  enormous  fragments  have  tumbled  down 
the  slope.  Above  this  floor  at  intervals,  appear  heavy  masses 
from  ioo  to  300  feet  thick,  of  shales  and  sandstones.  In  these 
are  the  coal  beds. 

As  the  strata  of  the  plateau  dip  some  four  or  five  degrees  to 
the  southwest,  the  “ basal  ” sandstone  and  its  overlying  coal  beds 
are  soon  brought  down  to  the  level  of  the  base  of  the  ravine, 
bringing  the  coal  within  easy  reach.  The  Victor  mine  is  well 
located  at  such  a point.  The  flat  of  the  ravine  affords  an  excel- 
lent site  for  the  coal  village,  and  the  bluffs  a good  elevation  for 
dumping  coal  into  the  railway  cars,  while  the  springs  at  the 
head  of  the  canon  can  be  brought  down  by  pipes  to  supply  all 
the  water  necessary  for  the  company’s  use.  The  main  opening  is 
up  a side*  ravine  and  the  coal  is  brought  down  from  it  to  the 
tipple  by  a gently  graded  tramway.  The  main  entry  which  is 
spacious  and  roomy,  enters  the  side  of  the  hill,  and  is  eight  feet 
high  by  ten  feet  wide,  developing  a coal  seam  six  feet  thick 
which  has  one  seam  of  bone  near  the  base.  Coal  was  being 
mined  at  the  time  of  our  visit  at  forty  cents  a ton,  the  company 
supplying  the  blasting  powder.  A neat  little  coal  village  was  in 
process  of  erection  adjacent  to  the  mine. 

This  property  has  but  lately  been  opened,  but  when  the 
works  are  complete  a capacity  of  500  tons  daily  is  anticipated. 
There  is  another  opening  some  distance  up  the  gulch  upon  a 
coal  seam  ten  feet  thick,  which  either  occurs  at  a higher  geolog- 
ical horizon  than  the  lower  series  or  else  attains  its  position  by 
faulting.  Time  did  not  allow  us  to  examine  it.  In  the  basal 
sandstone  below  the  coal  we  found  good  specimens  of  the  char- 
acteristic fossil  Halymenites  or  Fucoid  (seaweed). 

This  property  belongs  to  the  Victor  Company,  of  which  Mr. 
Delos  Chappel  is  manager. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


IOI 


Analysis  of  the  coal  of  the  Victor  mine,  by  Professor  Regis 


Chauvenet : 

Water 1.26 

Volatile  matter 36.40 

Fixed  carbon 53-10 

Ash  (very  light) 9.24 


100.00 

Sulphur 1. 1 1 


WALSENBURG  DISTRICT. ROUSE  MINE,  DENVER  FUEL  COMPANY. 

This  district  is  situated  near  the  north  end  of  the  great  Trinidad 
coal  plateau.  On  the  edge  of  this  plateau  and  away  from  it  to 
the  east,  down  the  Cuchara  river,  are  low  plateaus  of  shale  and 
sandstone  and  as  far  as  the  eye  can  reach  to  the  east,  are  scattered 
isolated  mesas  recording  the  once  great  eastern  extension  of  the 
coal  plateau.  From  the  top  of  most  of  these  mesas  the  coal  has 
been  eroded  off,  either  exposing  the  basal  sandstone  of  the  coal, 
or  else  the  softer  marine  Cretaceous  shales  of  the  Fox-hill  group 
underlying  the  Laramie  coal  series. 

The  plateau  in  this  neighborhood  is  riven  at  intervals  by  a 
series  of  eruptive  dykes  some  of  a porphyritic,  others  of  a basaltic 
type,  the  former  appear  to  be  directly  connected  with  a great  line 
of  eruption  running  north  and  south  toward  the  western  portion 
of  the  plateau  and  culminating  in  the  Spanish  peaks,  La  Veta, 
Sheep  and  Silver  mountains.  From  all  these  peaks  as  from 
centers  of  eruption  numerous  porphyritic  dykes  radiate.  The 
dykes  of  basalt  which  run  out  for  miles  on  the  plains  may  have 
been  the  result  of  a later  eruption  along  the  original  line  of 
volcanic  activity.  These  dykes  form  conspicuous  ridges  or  hog- 
backs at  various  intervals,  some  close  together,  some  far  apart. 

Those  appearing  conspicuously  above  the  surface  of  the 
present  prairie  were  once  surrounded  by  the  plateau  strata  which 
have  been  eroded  away,  leaving  the  harder  dykes  standing  out  in 
bold  relief.  Others  are  met  with  traversing  the  cliffs  of  the 
plateau  and  running  along  the  top  of  it.  Others  again  are  buried 
under  drift  and  betray  their  presence  by  fragments  of  hard  black 
rock  lying  on  the  surface.  The  mines  at  present  opened,  viz:  the 


102 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


Walsenberg,  the  Rouse  and  the  Pictou  mines,  though  several 
miles  apart,  have  in  their  workings,  all  encountered  one  or  more 
of  these  dykes  or  their  offshoots,  showing  how  much  the  strata 
must  be  interpenetrated  by  these  volcanic  phenomena. 

Leaving  the  little  town  of  Walsenburg  which  is , situated  on 
the  banks  and  ancient  bed  of  the  Cuchara  river,  we  drive  for  six 
miles  in  a southerly  direction  along  the  edge  of  the  great  plateau. 

The  prairie  beneath  our  feet  is  composed  of  the  marine 
Cretaceous  shales,  in  which  are  occasionally  found  fossil  sea  shells. 
Above  this  for  some  300  to  500  feet  arise  the  abrupt  cliffs  of  the 
plateau.  In  these  a wide  bay-like  opening  occurs,  leading  into 
the  plateau  by  a shallow  ravine.  Here  are  the  workings  of  the 
Rouse  mine.  (See  Plate  V.)  A great  semi-circular  tramway, 
with  a double  tipple,  raised  on  lofty  trestles,  spans  the  ravine,  one 
tramway  sloping  gently  from  the  coal  openings  on  the  north  side 
of  the  ravine,  the  other  correspondingly  from  those  on  the  south 
side,  uniting  in  the  center  at  a double-tipple,  by  which  the 
coal  is  discharged  into  the  cars  of  the  Rio  Grande  railway 
which  has  a side  track  six  miles  in  length  from  the  main  line  to 
this  point.  The  village  of  the  company  lies  inside  this  semi-circular 
rampart.  The  plant  consists  of  two  or  three  large  engine  houses 
conected  with  the  workings. 

There  are  two  tail-rope  engines  which  severally  draw  in  and 
out  the  loaded  and  empty  cars  through  the  main  entries  of  the 
principal  openings  by  means  of  wire  ropes  passing  over  double 
cylinders  and  revolving  in  an  endless  rope  system.  Two  Ramsey 
box-car  loaders  are  also  worked  by  steam.  The  engines  are  125 
horse  power.  Everything  connected  with  these  mines  is  con- 
ducted on  the  latest  and  most  improved  principles,  a great  deal 
of  machinery  and  steam  power  being  employed.  The  main 
drawback  to  the  property  is  the  lack  of  water  in  the  immediate 
vicinity,  all  water  for  the  use  of  the  engines  having  to  be  brought 
by  train  for  a distance  of  some  miles.  On  the  south  side  of  the 
ravine  near  the  trestle  is  one  of  the  main  openings,  entering  the 
gently  sloping  bank  of  the  bluff  at  a slight  incline  of  four  degrees 
to  the  southwest,  which  is  the  average  dip  of  the  coal  in  this 
area.  It  follows  down  the  coal  from  its  outcrop  on  the  surface. 
At  some  distance  from  the  opening  an  air-shaft  descends  fifty 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


103 


feet  into  the  underground  workings.  Through  the  center  of  the 
shallow  ravine,  and  of  the  property,  runs  the  railroad  track.  On 
the  opposite  or  north  side,  in  a gently  sloping  park  between  the 
bluffs,  are  the  two  north-side  main  entries,  with  corresponding 
air  shafts  at  intervals.  The  locality  is  a well  chosen  one  for  the 
coal  workings,  and  a pretty  situation  for  the  neat  little  village  of 
new  frame  houses  nestling  among  the  pinon  trees.  The  gentle 
slope  of  the  bluffs  on  either  side  give  the  necessary  elevation  and 
dip  for  the  tramways  leading  from  the  mines.  The  railway  runs 
the  length  of  the  property,  at  a level  conveniently  lower  than  the 
outlets  of  the  mine.  The  coal  can  be  worked  on  both  sides  of 
the  ravine,  tributary  to  one  discharging  point.  The  coal  is 
easily  accesible  from  the  surface  downwards,  lying  but  fifty  feet 
vertically  below  the  deepest  point,  so  that  air  shafts  can  be  run 
to  the  surface  without  expense  or  difficulty,  thus  securing 
good  ventilation,  erosion  having  removed  a great  amount  of  rock 
from  above  the  surface  of  the  coal.  The  haulage  on  the  gentle 
dip  is  easy  and  without  strain  on  the  machinery. 

Our  illustration  will  give  an  idea  of  the  picturesque  surround- 
ings of  the  camp  and  the  location  of  the  works  and  mine.  The 
plateau  bluffs  rising  above  the  village  are  rounded,  and  about  100 
feet  in  height,  more  or  less  covered  with  pinons  and  separated 
from  one  another  by  little  ravines.  Beyond  the  bluffs  and  the 
plateau,  some  twenty  miles  distant,  rise  the  magnificent  twin 
Spanish  peaks  and  beyond  them  some  thirty  miles  off  are  the 
long  white  crests  of  the  Sangre  de  Cristo  range.  A little  to  the 
northwest  and  in  line  from  the  Spanish  peaks  are  the  La  Veta 
and  Silver  mountains,  all  of  the  same  volcanic  origin.  Still 
further  to  the  north  is  the  lofty  terminus  of  the  Greenhorn  range 
whose  summit  is  also  capped  with  eruptive  rock.  The  intervening 
country  is  a pinon-covered  rolling  one,  part  plateau  and  part 
uplifted  hogbacks  of  sedimentary  rocks.  The  latter  occur  mainly 
along  the  flanks  of  the  volcanic  peaks,  and  generally  along  the 
border  of  the  Sangre  de  Cristo  range.  Here  and  there  rising 
above  the  strata  may  be  seen  one  of  those  wall-like  dykes  that 
intersect  this  remarkable  region.  For  many  miles  to  the  west, 
southwest,  and  north,  the  monotonous  coal  plateau  prevails.  In 
the  neighborhood  of  the  peaks,  lower  Cretaceous  rocks  are 


104 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


brought  to  light  by  uplift  and  erosion,  and  also,  according  to  Mr. 
R.  C.  Hills,  an  enormous  thickness  of  Tertiary  rock  gathers 
around  the  west  Spanish  peak.  The  Triassic  and  Carboniferous 
prevail  west  of  the  peaks  and  are  uptilted  against  the  Sangre  de 
Cristo  range  of  granite.  The  Laramie  plateau  to  the  east  of  this 
fringe  of  older  strata  forms  a wide  shallow  synclinal  basin  or 
trough  tipped  up  in  the  neighborhood  of  the  Spanish  peaks  and 
dipping  easterly,  but  some  twenty  miles  east  of  the  peaks,  as  for 
instance  at  Walsenburg  and  the  Rouse  mine  and  for  some  thirty 
miles  or  more  down  to  Trinidad,  the  dip  is  in  an  opposite  direc- 
tion, viz;  to  the  southwest,  thus  forming  a shallow  trough.  To 
accomodate  itself  to  the  prevailing  dip  of  the  plains  the  plateau 
must  again  have  formed  an  arch  and  again  dipped  east.  This  we 
believe  is  found  to  be  the  case  some  thirty  miles  east  of  the  Rio 
Grande  track  The  top  of  the  arch  has,  however,  been  eroded 
away  for  miles,  leaving  only  a degraded  outlie  or  mesa,  here  and 
there,  to  mark  its  former  existence.  If  we  reconstruct  therefore 
the  ancient  coal  plateau  in  its  entirety,  we  should  have  two  folds, 
one  a synclinal  trough  to  the  west,  an  another  an  anticlinal  arch 
to  the  east. 

About  half  a mile  to  the  east  of  the  Rouse  mine  the  “ basal 
sandstone  ” caps  the  top  of  the  bluff  from  which  the  accompany- 
ing sketch  was  made.  The  coal  had  been  removed  from  it  by 
erosion.  The  southwest  dip  of  this  bluff  shows  that  its  sand- 
stone cap  would  eventually  pass  under  the  coal  found  in  the 
Rouse  workings.  As  the  dip  is  four  degrees  to  the  southwest, 
the  entries  in  following  the  coal  have  to  be  driven  down  in  that 
direction,  consequently,  traction  engines  drawing  laden  cars  up  a 
gentle  incline,  are  a necessity  in  the  mines  of  this  district,  while 
in  some  others,  as  at  Trinidad  where  the  dip  is  downward  toward 
the  outlet  of  the  mine,  only  gravitation  is  required.  The  traction 
wire  ropes  on  this  south  side  pass  down  through  a bore  hole  near 
the  end  of  the  main  entry  for  fifty  feet,  then  along  the  line  of  the 
track  through  the  entire  length  of  the  entry  over  a series  of  rol- 
lers, and  then  over  a number  of  trestles  on  the  surface,  the  wire 
being  connected  with  a stationary  engine,  thus  the  traction  power 
of  the  rope  works  in  an  endless  ellipse. 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


105 


The  coal  will  be  found  inexaustible  as  the  workings  are 
pursued  under  the  plateau. 

The  slope  on  the  south  side  descends  by  a grade  of  four 
degrees  in  a direction  south  20°  west ; the  tunnel  is  wide  and 
roomy,  about  eight  feet  in  height,  developing  a six  foot  coal  seam, 
it  is  wide  enough  to  accomodate  three  separate  tracks,  two  of 
which  are  at  present  in  use.  Heavy  timber  is  used  to  support 
the  roof,  which  is  shaly  and  poor.  At  some  distance  within  the 
entry  a dyke  of  basalt  is  encountered  as  a formidable  obstacle, 
for  the  workings  have  had  to  meet  it  diagonally  instead  of  at 
right  angles,  and  though  its  thickness  is  not  more  than  thirty 
Let,  this  cutting  at  an  angle  involves  a much  greater  distance. 
The  dyke  is  of  adamantine  hardness,  using  up  the  drills  very 
quickly,  but  blasting  well.  For  thirty  feet  on  either  side  of  this 
dyke  the  coal  has  been  changed  to  a kind  of  hard,  natural  coke 
with  its  cleavage  planes  at  right  angles  to  the  sides  of  the  dyke. 
Fragments  of  coal  over  a yard  in  diameter  have  also  been  caught 
' in  the  molten  embrace  of  the  lava  dyke  and  similarly  changed 
to  coke.  Little  seams  of  iron  pyrites  are  found  near  the  dyke. 
In  some  places,  either  by  calcination  or  the  access  of  water 
through  cracks,  the  basalt  is  reduced  to  a soft  kaolinic  condition. 
The  usual  “ butt  and  face  ” cleavage  of  the  coal  as  it  nears  the 
dyke  is  deflected  into  a slanting  direction.  Owing  to  the  strike 
of  the  dyke,  and  the  necessitated  following  of  a southeast  direc- 
tion in  developing  the  mine,  rooms  and  entries  for  a while  are 
liable  to  come  across  this  same  obstruction.  The  coal  immediately 
adjacent  to  the  coke  does  not  seem  to  be  affected,  further  than 
that  it  is  of  unusually  good  quality,  the  transition  from  coal  to 
coke  seems  quite  abrupt.  No  bone  or  shale  partings  are  observ- 
able in  the  coal  seam,  but  near  the  lower  portion,  a thin  seam  of 
half  an  inch  of  soft  clay  occurs  continuously,  but  is  not  detri- 
mental to  the  coal,  which  may  be  considered  as  absolutely  free 
from  foreign  impurities  and  maintains  its  thickness  and  character 
throughout  the  mine  with  great  uniformity. 

The  coal  breaks  in  large  hard  blocks  of  a bright  and  anthra- 
citic lustre,  is  not  affected  by  wheathering,  and  is  said  to  stock 
well  in  the  coal  yards. 


106  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

The  workings  on  the  opposite  side  of  the  ravine  are  similar 
to  those  we  have  described,  with  the  exception  that  they  are  not 
troubled  with  dykes,  but  have  met  with  a fault  which  dropped  the 
coal  seam  twenty- five  feet. 

The  length  of  the  main  entry  on  the  south  side  is  1,000  feet, 
with  rooms  and  side  entries  branching  off  from  it.  The  length 
of  the  main  west  entry  on  the  north  side  is  800  feet.  There  are 
in  all  about  7,500  feet  of  entries  and  cross  entries,  and  about  150 
rooms  now  working.  The  coal  seam  is  six  feet  thick,  with  shale 
roof  and  sandstone  floor.  These  mines  are  not  over  a year  old, 
but  have  accomplished  a large  amount  of  development  in  that 
time.  In  favorable  seasons,  the  daily  output  is  1,300  tons.  The 
principal  markets  are  along  the  Burlington  road  to  Nebraska  and 
Kansas,  also  to  Pueblo  and  Denver.  There  are  two  tail-rope 
engines,  one  on  the  north  the  other  on  the  south  side;  the  rope 
on  the  north  side  is  900  feet  long,  that  on  the  south,  1,500.  The 
tail-rope  engines  are  125  horse  power.  The  double-dump  trestle 
is  250  feet  long  and  fifty  feet  high.  Ventilation  in  the  mines  is 
at  present  good,  and  is  assisted  by  open  furnaces  and  by  air 
shafts ; fans  will  be  erected  when  needed.  There  is  no  gas  in  the 
mine,  and  the  workings  are  exceedingly  dry.  The  coal  is  said 
to  cake  bu? not  to  coke,  leaving  no  clinkers  in  the  fire,  but  only 
a white  ash.  Above  the  main  seam  is  a small  two  foot  seam  of 
coal  which  the  lava  has  entered,  and  spread  out  in  it  as  an  intru- 
sive sheet  along  the  line  of  least  resistance.  About  500  men  are 
employed.  The  coal  is  mined  by  pick  and  shovel  at  sixty  cents 
per  ton.  The  mines  belong  to  the  Denver  Fuel  Company. 

Analysis  of  the  Rouse  coal  from  the  south  side  entry,  by 
Professor  Tilden  : 


Water 2.66 

Volatile  matter 36.71 

Fixed  carbon  ...  5141 

Ash  (light  brown) 9.22 


10000 

Sulphur 1 *373 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


107 


PICTOU  MINES,  (SOUTHERN  COLORADO  COAL  CO.) 

AT  SULPHUR  SPRINGS. 

Returning  to  Walsenburg  we  examined  the  bluffs  on  the 
south  side  of  the  Cuchara  river.  These  belong  to  the  Fox-hill 
group  of  the  Cretaceous,  and  consist  of  a great  thickness  of  drab 
shales  underlying  the  coal  sandstones.  About  100  feet  below 
the  top  of  the  bluffs  is  a stratum  of  calcareous  concretions  of 
elliptical  shape  much  flattened  by  compression.  They  are  very 
hard,  but  owing  to  their  septarian  divisions  readily  break  up  into 
small  blocks.  We  could  find  no  fossils  in  them.  These  concre- 
tions have  been  thought  of  as  an  element  for  making  Roman 
cement.  They  are  often  so  close  together  as  to  form  a consecu- 
tive stratum  about  two  feet  thick. 

From  Walsenburg  we  crossed  the  valley  of  the  Cuchara  in  a 
northwest  direction  towards  a lofty  abrupt  ridge  which  we  found 
to  be  caused  by  a formidable  dyke  of  basalt,  running  northwest 
and  southeast  coming  up  through  the  coal  sandstone.  From  the 
top  of  this  we  descended  into  a narrow  valley  about  a half  a mile 
in  width,  bounded  on  the  northwest  by  a similar  and  parallel 
dyke,  but  not  of  such  formidable  thickness.  Through  the  center 
of  this  valley  flows  a stream  of  tepid  water  highly  charged  with 
sulphuretted  hydrogen,  which  issues  from  a powerful  spring  from 
the  underlying  coal  beds  between  the  two  dykes,  its  chemical 
elements  being  doubtless  derived  from  the  coal  seams. 

The  workings  of  the  Pictou  mine  with  its  accompanying 
trestle  tramway  and  tipples  discharges  coal  into  the  cars  of  a 
branch  line  of  the  Denver  & Rio  Grande  railroad,  (connecting 
with  the  main  line  at  Cuchara  station  some  six  miles  distant), 
and  occupies  the  center  of  the  valley.  Around  the  workings  is 
the  village  of  the  coal  miners.  The  several  openings  enter  the 
base  of  the  bluffs  on  three  seams  of  coal  which  outcrop  on  the 
surface.  The  dip  of  these  seams  is  seven  degrees  and  in  a south- 
west direction. 

The  upper  Lenox  seam  is  five  feet  six  inches  thick.  Thirty- 
five  feet  below  this  is  one  between  two  and  three  feet  thick. 
Fifteen  feet  below  this  again  is  the  Maitland  seam  four  feet  thick. 


I08  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

Entering  the  Maitland  incline  we  find  a good  deal  of  water 
dripping  from  the  roof.  This  water  by  its  sulphuretted  character 
has  a bad  influence  upon  the  iron  of  the  boilers  and  machinery, 
by  corroding  it  at  the  joints.  As  these  workings  are  leading 
down  in  the  direction  of  the  source  of  the  sulphur  springs,  pumps 
will  become  a necessity.  The  workings,  as  usual  in  narrow 
seams,  are  cramped.  Cross  entries  and  rooms  were  in  process  of 
excavation.  The  main  entry  has  so  far  reached  a distance  of  450 
feet.  The  seam  is  free  from  partings  of  bone  or  shale ; there  is  a 
half  inch  seam  of  clay  similar  to  that  of  the  Rouse,  to  which 
coal  seam,  except  in  thickness,  this  one  is  supposed  to  correspond. 
The  two  foot  seam  cut  by  the  main  entry  slope  is  not  of  sufficient 
size  to  work.  The  roof  of  these  seams  is  of  shale,  and  poor. 

Above  this  we  enter  the  slope  on  the  upper  or  Lenox  seam, 
the  main  entry  slope  owing  to  the  greater  size  of  the  seam  is  high, 
wide  and  commodious,  but  owing  to  a poor  roof  it  requires  care- 
ful timbering.  In  the  upper  part  of  this  seam,  which  is  five  feet 
six  inches  thick,  there  is  a shale  parting  about  one  foot  thick 
which  cuts  off  one  foot  of  coal  from  the  workable  thickness. 
This  parting,  together  with  the  overlying  foot  of  coal,  is  left  to 
strengthen  the  roof.  The  peculiar  structure  of  this  coal  consists 
of  a series  of  hard  spherical  concretions  from  the  size  of  an  egg 
to  a foot  or  more  in  diameter.  These  concretions  are  of  hard 
coal  with  an  anthracitic  polish  on  the  outside. 

The  coal  area  is  limited  on  the  north  and  south  by  the  paral- 
lel dykes,  but  not  so  toward  the  west.  There  are  other  workings 
in  this  area,  and  in  one  of  them  on  the  Maitland  seam  on  the 
north  side,  three  small  dykes  are  encountered,  each  about 
eighteen  inches  thick  and  about  fifty  feet  apart.  They  appear  to 
be  offshoots  from  the  main  dykes  and  are  not  met  with  near  the 
surface.  They  have  had  no  influence  on  the  coal.  This  mine  has 
been  only  a year  in  operation ; its  output  is  about  400  tons  daily. 
Forty  miners  are  employed.  A good  deal  of  this  coal  is  shipped 
to  Kansas.  The  company  is  the  Southern  Colorado  Company, 
of  which  J.  K.  Robinson  is  manager. 

Analyses  of  the  coal  of  the  Pictou  mines,  by  Professor  Regis 
Chauvenet  of  the  School  of  Mines  : 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


109 


LENOX  COAL  SEAM. 


Water 2.92 

Volatile  matter 41.18 

Fixed  Carbon 45 .36 

Ash  (very  light) 10.54 


100.00 

Sulphur 1.39 


MAITLAND  SEAM. 


Water 3.10 

Volatile  matter 38.12 

Fixed  Carbon 48.58 

Ash 10.20 


100.00 

Sulphur 2.04 


NORTH  WESTERN  END  OF  THE  COAL  PLATEAU. 

Beyond  the  Pictou  mines  and  the  property  of  the  Southern 
Colorado  Coal  Company,  the  Coal  Plateau  extends  some  seven 
or  eight  miles  further  to  the  northwest,  when  it  is  abruptly 
terminated  by  the  erosion  of  the  valley  of  the  Huerfano  River. 
A little  ravine  known  as  the  “ Coal  and  Carbon  Arroya  ” at 
the  base  of  the  plateau  forms  part  of  the  natural  northwestern 
boundary  line  of  the  coal  field.  Beyond  this  to  the  north  the 
broad  valley,  through  the  centre  of  which  the  Huerfano  River 
flows  is  underlaid  by  Fox  Hill  Cretacious  shales,  which  are  not 
coal-bearing.  We  found  some  Baculites  and  other  marine  shells 
thrown  out  of  prospect  holes  which  had  been  dug  in  a vain 
search  for  coal.  Wherever,  in  Colorado,  these  shales  are  found 
underlying  a tract  of  country,  it  is  useless  to  prospect  for  coal 
there.  The  shales  will  generally  show  some  fossil  shells,  and 
the  discovery  of  these  may  be  considered  a rough  guide  for 
identifying  these  particular  shales,  as  fossil  shells  are  rarely  found 
in  Colorado  in  any  other  set  of  strata.  In  this  region  the  pinon 
trees  are  also  a useful  guide,  for  they  generally  grow  on  the  coal 
bearing  strata,  but  rarely  on  the  non-coal-bearing  shales. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


i io 


North  of  the  river  is  the  terminus  of  the  Greenhorn  or  Wet 
Mountain  range  formed  of  Archean  rocks,  and  from  the  north, 
along  the  western  boundary  of  the  plateau,  stretches  a line  of 
eruptive  hills  of  “ Laccolitic  ” structure.  The  most  northerly  of 
this  group  is  Badito  or  Sugar-loaf  peak,  a laccolite,  whose  bald 
head  of  grey  volcanic  rock  peeps  up  above  a ring  of  mesozoic 
strata  tipped  up  on  all  sides  around  it.  In  a line  with  this  are 
smaller  hills  of  dark,  eruptive  rock,  called  the  Black  Buttes,  and 
a star-shaped  laccolitic  called  Silver  Mountain,  from  which 
radiates  a great  number  of  dykes.  Behind  these,  a little  to  the 
west  are  two  or  three  straight  topped,  steep  looking  hills,  called 
the  Sheep  and  Veta  Mountains ; all  of  eruptive  origin,  and  of 
laccolitic  structure  composed  ofporphyritic  rock.  These  laccolites 
according  to  Mr.  Hills,  are  thick  sheets  of  lava,  intruded  hori- 
zontally among  the  Colorado  Cretaceous  shales,  and  resting  upon 
them  as  a base.  The  strata  lying  above  these  thick  intrusions 
were  cracked  by  them,  and  lava  welling  up  through  the  cracks 
filled  them  with  dykes.  One  or  more  main  dykes  also  came  up 
from  depths  unknown,  as  feeders  to  the  main  intrusive  laccolites. 
These  eruptions,  according  to  Hills,  occurred  towards  the  middle 
of  the  Tertiary  period,  and  were  incident  to  upward  movements 
in  the  Sangre  de  Cristo  and  Wet  Mountain  ranges;  movements 
which  have  also  produced  the  foldings  we  find  in  the  coal  plateau. 

This  line  of  eruptive  hills  forms  the  approximate  western 
boundary  of  the  coal  fields  in  this  section.  On  the  east  the  coal 
plateau  is  limited  as  farther  south  by  the  erosion  of  the  great 
plains.  This  northern  section  of  the  plateau  preserves  the  same 
uniform  characteristics  we  have  found  throughout  it  as  far  as 
Trinidad.  It  is  tipped  up  along  the  eastern  edge  to  about  io 
degrees,  dipping  southwest,  forming  part  of  that  broad,  anticlinal 
arch  we  have  mentioned  before,  whose  continuity  eastward  has 
been  largely  removed  by  the  erosion  of  the  plains.  To  the  north 
also,  it  shows  the  influence  of  the  Greenhorn  uplift,  and  dips 
south,  while  to  the  southwest  it  is  uptilted  even  to  verticality  by 
the  movements  of  the  Sangre  de  Cristo  range;  thus  forming  a long, 
shallow  trough  between  its  eastern  and  western  margins.  A large 
area  around  and  west  of  the  laccolitic  hills,  extending  from  the 
HuerfanoRiver  on  the  north  to  the  Spanish  peaks  in  the  south,  has 


Adapted  from  Haydens  Surrey 


GEOLOGY  OE  COLORADO  COAL  FIELDS. 


hi 


been  shown  by  Mr.  Hills  to  be  covered  by  a great  thickness  of 
Tertiary  beds  lying  unconformably  on  both  the  upturned  Laramie 
and  Colorado  shales.  It  occupies  an  extensive  basin,  formed  by 
the  folding  of  these  latter  groups.  The  Tertiary  character  of 
these  deposits  has  been  further  proved  by  the  discovery  of  fossil 
turtles  and  mammalian  bones  of  Tertiary  type. 

All  along  the  eastern  and  northern  edge  of  the  plateau  the 
yellow  massive  basal  sandstone  rich  in  impressions  of  fossil 
Halymenites  is  seen  outcropping  and  immediately  underlying 
the  lower  coal  seams,  and  overlying  the  non-coal-bearing  Creta- 
ceous shales.  The  plateau  is  traversed  here  and  there  by  a 
parallel  system  of  dykes  of  basaltic  character  having  a general 
northeast  and  southwest  course.  One  of  these  dykes  we  pass 
near  the  boundary  line  between  the  Southern  Colorado  and  Pinon 
Company’s  properties  and  another  at  the  northeastern  corner  of 
the  plateau.  The  columns  of  the  dyke  resulting  from  cleavage 
fractures  at  right  angles  to  the  cooling  walls  lie  horizontally  like 
so  many  logs  of  wood  piled  one  on  top  of  the  other.  The  same 
phenomena  may  be  observed  in  a dyke  crossing  the  plains  a few 
miles  north  of  El  Moro.  The  isolated  “ Huerfano”  or  “ Orphan 
butte  ” is  also  the  relic  of  a dyke,  standing  prominently  by  itself 
in  the  Huerfano  valley. 

Outcrops  of  coal  are  shown  by  prospect  holes  all  along  the 
eastern  margin  of  the  Pinon  Company’s  property  at  the  usual 
horizon  above  the  basal  sandstone  and  occurring  at  intervals  up 
through  the  four  or  five  hundred  feet  of  sandstones  forming  the 
top  of  the  plateau.  According  to  Professor  Benjamin  Sadtler, 
who  examined  and  located  this  property  for  the  Pinon  Company, 
there  are  as  many  as  five  different  seams  at  intervals  above  one 
another  in  these  sandstones.  These  are  in  ascending  order : 

1.  — 9 feet  thick  with  two  partings  and  resting  on  the 

basal  sandstone. 

2.  — 4 feet  6 inches  fifty  feet  above  the  last. 

3.  — 3 feet  8 inches  seventy-five  feet  above  No.  2. 

4.  — 3 feet  3 inches  forty  feet  above  No.  3. 

5.  — 5 feet  two  hundred  feet  above  No.  4 and  near  the 

top  of  the  plateau. 


1 12 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


The  large  tract  adjoining  this  property  on  the  northwest 
together  with  that  of  the  Pinon  Company,  was  by  some  error  not 
included  in  the  coal  plateau  or  marked  as  coal  land  in  Hayden’s 
economic  map.  According  to  that  map  the  plateau  and  coal 
series  terminate  very  near  the  Pictou  mines,  whereas  both  the 
coal  and  plateau  extend  some  seven  or  eight  miles  to  the  north- 
west beyond  this  point.  A singular  oversight,  considering  that 
not  only  does  the  Halymenites  sandstone,  the  well  recognised 
floor  of  the  coal,  outcrop  all  around  the  tracts  in  question,  but 
coal  itself  in  several  seams  as  we  have  shown,  and  at  various 
places  comes  plainly  to  the  surface.  Along  the  Carbon  arroya 
these  brown  weathered  outcrops  of  coal  have  been  developed  at 
several  points  showing  one  seam  in  particular,  and  that  the  lowest, 
to  be  6 feet  thick  of  very  pure  coal,  with  scarcely  a trace  of  bone 
or  other  parting.  The  sandstones  too,  throughout  the  hill  above 
are  full  of  fossil  leaves,  such  as  Platanus,  fronds  of  Palmetto’s, 
and  traces  of  carbonized  vegetation,  proving  the  Laramie  coal- 
bearing character  of  the  entire  hill  of  strata. 

The  land  is  unquestionably  coal  land  of  a valuable  and  avail- 
able character,  and  from  the  practical  impossibility  of  irrigating  it, 
let  alone  the  shallowness  and  rocky  character  of  the  soil,  it  is  as 
valueless  for  agricultural  purposes  as  it  is  valuable  for  coal.  The 
same  applies  to  a large  marginal  area  outside  of  the  land  in 
question  which  is  as  certainly  coal  land  and  should  so  have  been 
represented  on  the  economic  map  of  the  Hayden  Geological 
Survey.  We  have  endeavored  to  make  an  approximate  correction 
of  this  map  in  plate  VI. 


CHAPTER  VIIL 


The  Durango  Coal  Region. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


ii5 


Chapter  VII. 

THE  DURANGO  COAL  REGION.* 

SOUTHWESTERN  COLORADO. 

From  the  Trinidad  region  we  set  out  to  examine  the  coal 
fields  of  southwestern  Colorado  whose  developments  at  present 
are  confined  to  the  neighborhood  of  the  city  of  Durango.  Our 
course  led  us  across  the  Sangre  de  Cristo  range  by  the  La  Veta 
pass,  thence  through  the  San  Luis  Park  and  over  the  Conejos 
range  into  the  plateau  country  of  southwestern  Colorado,  prin- 
cipally occupied  by  the  Ute  reservation ; thence  up  the  Animas 
river  to  Durango,  which  is  not  far  from  the  La  Plata  and  San 
Juan  mountains.  As  this  route  and  country  is  not  so  generally 
well  known  as  some  other  parts  of  Colorado,  we  shall  describe  its 
geological  features  in  some  detail.  Our  first  halt  was  at  the 
village  of  La  Veta  from  which  we  have  a near  view  of  the  Spanish 
peaks.  From  the  main  masses  of  the  peaks  we  see  long  dykes 
like  artificial  walls  of  masonry  radiating  in  various  directions.  The 
eastern  peak  is  composed  of  one  solid  mass  of  lava  and  is  united 
to  the  western  peak  by  a saddle  of  the  same  material.  A large 
portion  of  the  latter  mountain  appears  to  be  composed  of  nearly 
horizontal  sedimentary  strata,  riddled  and  cemented  together  by 
dykes  and  volcanic  matter.  These  have  by  their  heat  metamor- 
phosed the  strata,  which,  according  to  Mr.  R.  C.  Hills,  belong  to 
the  Tertiary.  As  we  ascend  the  La  Veta  pass  we  are  not  far 
from  Dyke  or  Silver  mountain,  which,  as  its  name  implies,  con- 
sists of  a series  of  dykes  radiating  from  a common  center.  Far- 
ther on,  the  train  winds  around  the  foot  of  La  Veta  mountain. 
This  appears  to  be  a Laccolite,  for  the  red  sandstones  tip  up  all 
around  the  massive  central  cone  of  lava  at  an  angle  of  forty-five 
degrees.  The  cone  is  composed  of  a thick  mass  of  white  por- 
phyry, from  which  also  many  dykes  emanate.  As  we  climb  the 
Sangre  de  Cristo  range,  coarse,  red  sandstones  appear  dipping 


See  Frontispiece. 


1 1 6 GEOLOGY  OF  COLORADO  COAL  FIELDS. 

east,  these,  according  to  Endlich,  are  Carboniferous,  though  a 
good  deal  of  that  marked  on  the  map  as  Carboniferous  has  been 
shown  by  Mr.  Hills  to  be  Tertiary.  Several  dykes  appear  issuing 
from  the  granite.  Over  the  pass  we  find  limestone,  probably 
Lower  Carboniferous,  reclining  on  the  granite.  The  Sangre  de 
Cristo  range  seems  to  be  an  anticlinal  arch  of  granite,  once  over- 
laid by  Carboniferous  strata,  remnants  of  which  are  still  left. 

SAN  LUIS  PARK. 

We  descend  gradually  into  the  wide  prairie-like  basin  of  the 
San  Luis  Park  and  look  back  on  the  range  we  have  passed.  The 
most  striking  object  is  the  Sierra  Blanca,  the  highest  peak  in  the 
Rocky  Mountains,  a huge  mountain  mass  standing  somewhat  by 
itself.  The  top  of  the  mountain  is  excavated  by  glacial  agency 
into  a deep  amphitheater  not  unlike  a volcanic  crater,  from  which 
radiates  a series  of  canons  down  which  the  glaciers  once  moved 
from  their  source  above. 

From  Blanca  as  a center  the  snow-capped  Sangre  de  Cristo 
peaks  form  the  eastern  boundry  of  the  park.  To  the  south  a belt 
of  volcanic  cones,  dykes  and  lava-capped  table-mountains  circle 
around  and  unite  with  a great  lava  overflow  constituting  the 
Conejos  and  San  Juan  ranges,  which  form  the  park’s  western 
boundry.  This  volcanic  belt  suggests  the  formation  of  a series 
of  cracks  around  the  rim  of  the  basin,  coincident  with  the  time 
of  its  folding  up  by  the  movements  of  the  surrounding  moun- 
tains. From  these,  eruptions,  mostly  of  basaltic  lava,  poured 
down  into  the  basin  and  assisted  in  forming  its  floor.  At  one 
period  the  entire  park  was  filled  with  a great  sheet  of  fresh  water 
which  has  left  behind  it  lake-beds  of  considerable  thickness,  so  if 
the  coal  stata  existed  at  all  in  this  area  they  are  covered  by  these 
later  formations.  Artesian  wells  have  been  sunk  with  good  suc- 
cess at  various  points  and  have  brought  up  water  from  moderate 
depth.  At  La  Jara,  a well  bored  only  80  feet  throws  up  a large 
volume  of  water  with  considerable  force  in  the  open  street  of  the 
town. 

At  Antonito  the  railway  station  is  built  of  a black  vesicular 
basalt  whose  cavities  are  filled  with  white  zeolites.  This  stone  is 
derived  from  lava  flows  which  emanated  from  a cone  surmounting 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 117 

a sloping  plateau  of  lava  about  six  miles  northwest  of  the  town. 
These  flows  grade  off  into  the  basin  of  the  park  at  a dip  of  five 
to  eight  degrees.  This  hill  is  suggestive  of  a true  volcanic  crater, 
and  according  to  reports,  a cup  shaped  cavity  occurs  at  the  sum- 
mit. This  crater  together  with  a line  of  dykes  and  volcanic  out- 
bursts forms  a preliminary  fringe  to  the  Conejos  range  which  we 
presently  enter  through  a series  of  table-lands  and  terraces  of  lava 
with  occasional  patches  here  and  there  of  stratified  “tuff”  and 
further  on  heavy  masses  of  volcanic  “breccia”  eroded  into  mon- 
uments, “ hoodoos,”  and  other  curious  forms  which  have  given 
the  name  to  the  canon  of  “Toltec”  gorge.  The  thickness  of  this 
lava  is  at  least  2,000  feet  as  we  see  it  shown  in  sections  in  the 
gorge,  at  the  narrowest  point  of  which  a spur  of  granite  appears, 
upon  which  the  lava  rests  directly,  and  from  this  point  for  some 
miles  granite  continues  with  only  a slight  covering  of  lava.  Thus 
this  range  appears  to  have  been  a granite  uplift  flooded  by  lava. 
The  blocks  of  lava  in  the  “ breccia”  are  some  times  three  feet  in 
diameter  and  several  hundred  pounds  in  weight. 

UTE  RESERVATION  IN  SOUTHWESTERN  COLORADO. 

On  emerging  from  this  range  we  descend  into  the  well 
timbered  valley  of  the  Chama  river  and  look  down  upon  the 
region  of  southwestern  Colorado,  characterized  by  table-lands, 
consisting  principally  of  the  Laramie  coal  series  underlaid  by  the 
Fox-hills  Cretaceous  shales,  traversed  here  and  there  by  eruptive 
dykes  which  have  sent  outflows  of  lava  over  some  of  the  plateaus. 
Thus  it  is  a repetition,  only  on  a much  grander  scale,  of  what  we 
have  described  in  the  Trinidad  region. 

The  plateaus  with  their  attendant  coal  seams  extend  over 
hundreds  of  square  miles,  cut  up  at  intervals  by  canons  and  river 
courses  into  tables  and  castles,  and  tilled  up  and  interrupted 
towards  the  northwest  by  the  volcanic  La  Plata  and  San  Juan 
mountains.  It  is  scarcely  an  exaggeration  to  say  that  before  us 
as  far  as  the  eye  could  reach,  lay  one  vast  coal  field  extending 
beyond  the  limits  of  Colorado  into  Utah  and  Arizona. 

So  far  as  we  could  judge  from  the  train,  this  plateau  tips  up 
slightly  against  the  Conejos  range,  and  emerges  from  under  its 


1 8 GEOLOGY  OF  COLORADO  COAL  FIELDS. 

lava  cap.  In  the  valley  we  soon  observe  the  yellow  “ basal  sand- 
stone ” capping  a table  land  of  shale  600  feet  in  height,  consisting 
of  the  Fox-hills  group,  out  of  which  the  valley  of  the  Chama  has 
been  hollowed,  and  to  which  it  owes  its  fertility.  The  western 
dip  (three  degrees)  of  the  strata  gradually  brings  them  together 
with  the  overlying  coal  beds  to  the  level  of  the  valley,  a descent 
hastened  near  Monero  by  faulting.  Here  the  coal  is  mined  by 
the  Rio  Grande  close  to  the  railway  track.  Some  fine  looking 
yellow  sandstone  is  being  quarried  near  the  mines. 

For  miles  we  follow  the  montonous  plateaus  to  Amargo 
where  a valley  about  five  miles  wide  has  been  hollowed  out  of 
the  group.  A little  beyond  the  station  some  remarkable  dykes 
of  basalt  cross  the  valley  in  an  east  and  west  direction,  and  can 
be  easily  followed  for  a long  distance  by  their  wall-like  outlines 
and  dark  color  as  they  ascend  the  cliffs  of  sandstone  and  enter 
the  plateaus,  maintaining  a parallelism  as  exact  as  though 
laid  off  by  a compass.  Four  of  these  little  parallel  dykes  from 
three  to  four  feet  wide  and  a few  feet  apart  are  passed  close  to 
the  track  at  Navajo  station,  and  further  on  a dozen  of  them  may 
be  seen  running  in  parallel  groups  through  the  natural  cleavage 
joints  of  the  sandstone,  which  they  doubtless  enlarged  and  filled. 

Not  all  of  these  castles  and  table  lands  carry  coal,  for  at  some 
places,  as  at  Caracas  station,  the  coal  has  been  shorn  from  the  top 
of  them,  only  however,  to  be  resumed  again  at  Arboles.  From 
Arboles  to  La  Boca  station  the  coal  appears  to  be  overlaid  by 
some  600  feet  of  Tertiary  beds,  consisting  of  variegated  pink, 
maroon,  and  greenish  shales  and  sandstone,  forming  table  lands, 
in  which  but  little  coal  may  be  expected. 

In  our  course  through  this  well  watered  country  we  cross 
several  streams  tributary  to  the  San  Juan  river,  such  as  the  Piedro, 
Piney,  Navajo,  etc.,  and  for  some  distance  keep  along  the  banks 
of  the  San  Juan  itself,  a fine  stream  from  50  to  100  yards  wide, 
having  considerable  fall.  Between  La  Boca  station  and  Ignacio, 
detatched  mesas  and  outliers  of  the  series  occur,  but  the  prevailing 
rock  is  the  Fox-hill  shale,  which.continues  till  we  near  Durango. 
As  we  approach  this  town,  many  square  miles  to  the  south  are 
occupied  by  low  mesas  of  reddish  brown  Tertiary  strata,  the  coal 
plateaus  swinging  off  more  to  the  north  along  the  flanks  of  the 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  119 

La  Plata  and  San  Juan  mountains.  This  region  at  present  belongs 
to  the  Utes,  and  is  characterized  by  low  table  lands  often  well 
timbered  and  intersected  by  numerous  streams  and  water  courses. 
The  fall  of  these  streams  is  such,  that  ditches  from  them  could 
easily  be  carried  over  the  mesas,  and  irrigate  large  tracts  ol 
country  now  unutilized.  It  is  a well-watered  “promised  land” 
of  the  future.  The  Durango  people  are  impatiently  awaiting  the 
time  when  the  Utes  shall  go,  and  they  shall  enter  in  and  possess 
this  good  land  with  its  coal,  grazing  and  farm  lands.  They  are 
also  looking  eagerly  for  a railroad  line  into  New  Mexico  or 
Arizona,  as  a southern  outlet  and  market  for  their  coke  and  other 
products.  As  we  ascend  the  Animas  river,  the  hitherto  flat  strata 
of  the  mesas  begin  to  bend  upwards  at  an  angle  of  15  to  30 
degrees,  caused  by  the  uplift  of  the  La  Plata  and  San  Juan  moun- 
tains, whose  snowy  peaks  appear  to  the  northwest,  and  around 
whose  flanks  a great  thickness  of  strata  from  the  Silurian  to  the 
Tertiary  is  lifted  up,  and  among  them  the  Laramie  coal  beds,  and 
their  underlying  Fox- hill  shales. 

GEOLOGY  OF  THE  DURANGO  DISTRICT. 

The  first  in  order  as  we  ascend  the  river  is  the  Tertiary,  form- 
ing the  flank  of  a Laramie  hogback,  whose  thickness  is  upwards 
of  1,000  feet;  a reference  to  the  colored  illustration  will  show 
this  relation.  A good  place  to  bore  for  artesian  water,  gas,  or 
oil,  would  be  somewhere  near  the  point  below  which  the  Tertiary 
strata  bend  down  from  the  back  of  the  ridge  and  pass  under  the 
flat  mesas  of  the  Ute  reservation,  one  side  of  a basin  being  thus 
formed.  The  great  Carbonero  coal  seam,  of  which  we  shall 
speak  hereafter,  would  be  tapped  by  such  a bore  at  a depth  not 
exceeding  2,000  feet.  As  this  seam  carries  an  extraordinary 
amount  of  gas  in  it  when  it  lies  below  water  level,  it  is  not 
unreasonable  to  suppose  that  this  gas  might  be  tapped  at  the 
point  we  suggest,  some  six  or  eight  miles  from  the  town  of 
Durango.  The  train  now  carries  us  along  the  course  of  the 
Animas,  past  this  mass  of  uplifted  strata.  The  Tertiary  beds 
consists  of  thick,  reddish,  rusty  conglomerate  resting  upon  shales 
and  heavy-bedded  sandstones  of  the  Laramie  group.  The  first 
hogback  or  block  of  strata  ends  abruptly  in  a cliff  about  1,000 


120 


GEOLOGY  OF  COL  OF  A BO  COAL  FIELDS. 


feet  high,  composed  of  Fox-hill  shales  capped  by  the  basal  sand- 
stone and  overlying  coal  beds. 

In  this  mass  of  strata  there  are  two  separate  belts  of  coal,  the 
lower  overlying  the  basal  sandstone  and  containing  a half  a dozen 
small  seams  from  one  to  five  feet  in  thickness.  These  are  devel- 
oped in  another  part  of  the  field  by  the  San  Juan,  Shores,  Porter, 
Black  Diamond  and  City  Bank  mines,  most  of  whose  workings 
are  in  seams  of  very  good  coal,  rarely  exceeding  four  feet  in 
thickness. 

A hundred  or  more  feet  above  these  is  the  upper  belt  of  coal 
seams  of  enormous  thickness  known  as  the  Carbonero,  from  the 
prominent  mine  of  that  name.  This  belt  has  been  traced  for  a 
great  distance  ; it  consists  of  an  aggregate  of  many  coal  seams  of 
varying  thickness.  These  are  sometimes  so  close  together  that  they 
constitute  almost  a solid  body  of  coal,  split  up,  however,  by  numer- 
ous shale  partings;  at  other  times  the  different  component  seams 
stand  well  apart  and  can  be  worked  separately.  This  belt  has 
been  traced  from  Durango  to  Florida  and  beyond  a distance  of 
70  miles,  and  might  doubtless  be  followed  much  further.  It  is 
this  belt,  no  doubt,  to  which  Professor  Newberry  refers  when  he 
says:  “ On  the  San  Juan  and  its  tributaries  is  quite  an  extensive 
coal  field,  and  I have  ridden  many  miles  along  the  north  side  of 
this  river  where  its  banks  contain  a continuous  coal  seam  from  30 
to  50  feet  in  thickness.  This  is,  however,  like  all  such  great 
seams,  far  from  homogeneous,  layers  of  good  coal  2 or  3 feet  in 
thickness,  alternating  with  layers  of  slaty  coal ; but  near  the 
mouth  of  the  Animas  I noticed  another  seam  6 feet  in  thickness, 
which  was  fairly  uniform  in  composition.”  Near  Durango  these 
seams  will  aggregate  80  to  90  feet  of  coal,  of  which  a good  deal 
is  workable.  The  belt  appears  to  run  along  the  Atlantic  Divide, 
extending  down  to  Gallup  in  Arizona.  It  swings  around  the  La 
Plata  and  San  Juan  mountains  where  it  is  uplifted  by  those 
ranges,  and  again  becomes  horizontal  in  the  Montezuma  valley. 
Apart  from  the  distinct  outcrops  of  the  coal  itself  in  the  various 
ravines,  it  can  be  followed  even  from  a long  distance  by  the  eye, 
by  a sharply  defined  valley  which  it  makes  in  the  hogback,  often 
100  or  200  feet  deep;  the  soft  coal  having  yielded  to  erosion  more 
easily  than  the  confining  sandstones.  In  the  neighborhood  of 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


1 2 I 


Durango  there  are  but  three  mines  in  this  belt — the  Carbonero,  on 
the  east  bank  of  the  Animas  close  to  the  Rio  Grande  track  and 
the  bed  of  the  river,  another  some  five  miles  east  of  it  called  the 
La  Plata,  and  a third  in  the  hogback  west  of  the  river  called  the 
California.  Only  the  La  Plata  is  at  present  working,  the  market 
for  coal  being  confined  to  the  city  of  Durango  and  some  of  the 
mining  towns,  for  which  four  or  five  mines  nearer  the  city  are 
competitors.  But  a time  will  come  when  the  Ute  reservation 
being  thrown  open,  an  increased  population  and  greater  railroad 
facilities  will  cause  many  new  prospects  to  be  developed  upon 
this  phenomenal  coal  belt  of  Colorado. 

Proceeding  up  the  river  we  are  apprised  of  the  reason  of  the 
steep  ending  up  of  the  hogback  by  the  appearance  of  a second 
very  similar  ridge  rising  from  the  base  of  the  last.  The  shales 
are  likewise  capped  by  the  same  basal  sandstone  upon  which  re- 
mains, however,  but  ioo  or  more  feet  of  coal  bearing  strata. 
Such  a duplication  of  strata  within  an  interval  of  a mile  or  so, 
suggests  a fault,  and  that  the  lower  bench  was  once  a continuous 
part  of  the  tipper  one,  from  which  it  has  broken  off  and  fallen 
down,  while  the  other  remained  constant  or  was  in  turn  uplifted. 
As  also  we  only  find  the  lower  series  of  smaller  coal  seams  in 
this  second  hogback,  we  conclude  that  after  it  fell  down,  the  up- 
per or  Carbonero  belt  was  eroded  off  from  it,  leaving  only  the 
lower  seams.  This  is  confirmed  by  finding  at  the  La  Plata  mine, 
where  the  strata  are  entire,  seams  that  correspond  with  those  of 
the  Porter  and  San  Juan  mines,  overlaid  by  the  whole  of  the 
thicker  group.  Our  illustration,  which  was  taken  from  above  this 
mine  will  make  this  clear  and  also  show  the  nature  of  the  fault. 
The  two  series  in  the  twin  hogbacks,  originally  but  ioo  feet 
apart,  are  now  separated  by  a valley  a mile  or  more  wide  of 
faulted  ground  in  which  the  Shores  mine  is  working  on  a four 
foot  seam,  and  by  a thickness  of  1,000  feet  of  shales.  The 
greater  Carbonero  series  is  seen  swinging  away  towards  the 
west  in  the  direction  of  the  Montezuma  valley,  while  the 
lower  series  keeps  on  towards  the  La  Plata  and  San  Juan 
mountains.  Numerous  ravines  cutting  through  the  soft  Fox-hill 
clays  dissect  these  hogbacks,  leaving  here  and  there  prominent 
castle-rocks  as  shown  in  the  picture,  close  to  the  town.  The  city 


122 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


of  Durango,  with  its  handsome  villas,  fine  hotel,  and  smelting 
works,  is  located  in  the  valley  of  the  Animas  upon  the  lower 
portion  of  these  Fox-hill  shales,  covered  by  a considerable  thick- 
ness of  glacial  drift.  North  of  the  town  we  follow  the  Animas 
river  up  into  its  beautiful  canon,  and  in  ascending,  pass,  geologi- 
cally, down  through  the  whole  strata  of  the  earth’s  crust,  period 
following  period  of  uplifted  strata,  down  to  the  granite  “ bedrock.” 
First,  underneath  the  Fox-hill  shales,  outcrops  the  hard  white 
sandstone  of  the  Dakota  Cretaceous.  The  later  cannot  deeply 
underlie  the  streets  of  the  city,  and  from  it  probably  the  projected 
artesian  well,  when  bored,  will  derive  its  water,  contained  in  the 
joints  of  the  sandstone,  well  confined  by  overlying  shales.  The 
dip  of  these  strata  is  to  the  south.  Next  in  order  and  beneath 
this  are  a few  hundred  feet  of  variegated  shales  belonging  to  the 
Jurassic.  Then  a massive  cream  colored  sandstone  appears,  cap- 
ping the  Triassic  rocks,  which  consist  of  a great  thickness  of  red 
conglomerate  sandstone.  Beneath  these  again  at  Tremble  Springs 
we  see  the  purplish  sandstones  of  the  upper  Carboniferous,  and 
below  them  the  Lower  Carboniferous  and  Silurian  limestones  and 
finally  the  Cambrian  quartzite  resting  upon  “bedrock”  granite 
near  Rockwood. 

As  we  approach  the  Needles  and  the  town  of  Silverton,  we 
find  enormous  volcanic  overflows  covering  all  strata  alike  and 
overwhelming  them  for  hundreds  of  square  miles  beneath  a thick- 
ness of  from  2,000  to  5,000  feet  of  lava  constituting  the  San  Juan 
mountains. 

This  completes  the  geological  features  of  this  district,  which 
will  be  better  understood  by  reference  to  the  colored  engraving 
and  its  accompanying  sections.  The  scene  depicted  in  the  sketch 
shows  the  peculiar  plateau  characteristics  of  this  region  and  was 
selected  by  the  writer  as  one  of  the  most  striking  illustrations  of 
a great  coal  field  to  be  met  with  in  Colorado  or  elsewhere,  a 
field  of  inexhaustible  resources  awaiting  the  removal  of  the  Ute, 
the  advance  of  civilization,  and  the  opening  up  of  more  extensive 
markets. 


THE  PORTER  COAL  MINES. 

A small  creek,  called  Lightner  creek,  comes  into  the  Animas 
from  the  west,  about  half  a mile  from  the  city.  It  cuts  through 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


23 


the  shales  and  lower  sandstones  of  the  coal  series,  and,  as  we 
ascend  the  creek,  the  western  dip,  at  about  four  miles  from  its 
mouth,  brings  the  coal  sandstones  down  to  the  creek  level,  and 
here  the  Porter  mines  are  located,  with  several  openings  on 
different  seams.  The  first  opening  is  a tunnel,  1,800  feet  long, 
passing  clear  through  the  hill  and  coming  out  on  the  other  side 
in  a little  ravine,  on  the  opposite  side  of  which  the  tunnel  is 
being  continued  for  a few  feet  on  the  outcrop  of  the  seam.  A 
bridge  thrown  across  this  ravine  can  connect  with  the  main 
tunnel,  and  carry  the  coal  on  a downward  dip  to  the  general 
dischargingpoint.  The  seam  developed  is  3 feet  6 inches,  of  very 
good  pure  coal,  unalloyed  by  bone  or  shale.  The  mine  is  developed 
on  the  Long-wall  system,  and  rooms  thirty  feet  square  are  run 
off  from  the  main  entry.  Some  difficulty  was  experienced  in  the 
early  days  of  the  development  by  a heavy  roll  encountered  near 
the  entrance  on  the  south  side,  which  completely  pinched  out 
the  seam.  When  this  was  passed,  however,  the  seam  resumed 
its  average  size.  Some  small  step  faults  of  about  three  feet  fall 
occur  locally.  They  mine  three  feet  six  inches  of  pure  coal,  and 
leave  a foot  of  bony  coal  next  the  roof.  The  latter  is  of  a 
massive  sandstone,  and  unusually  good,  requiring  but  a few  short 
“ stulls  ” to  sustain  it.  In  places  where  the  coal  has  been  worked 
out,  these  are  slowly  crushing.  The  floor  is  of  shale.  Leaf 
impressions  are  common  in  the  sandstone.  The  main  entry  is 
eight  feet  high,  six  feet  wide  and  1,800  feet  long.  The  track  is 
2 feet  6 inches  wide.  The  coal  is  hard  and  lustrous,  breaking  in 
firm,  square  blocks,  which  show  distinct  cleavage  faces.  The 
dip  is  four  degrees  to  the  south,  allowing  an  easy  down  grade  for 
laden  cars  to  the  entrance.  A side  track  is  contemplated,  four 
miles  long,  connecting  with  the  main  line.  At  present  only 
development  work  is  going  on,  and  but  few  men  are  employed. 
When  running  full,  they  claim  a capacity  of  500  tons  daily. 
These  mines,  with  those  of  the  San  Juan,  are  the  chief  sources 
of  the  coal  supply  of  the  town.  The  coal  also  makes  excellent 
coke. 

This  Porter  seam  appear  to  be  the  lowest  workable  seam  in 
this  group,  two  smaller  seams,  one  eighteen  inches  and  another 
two  feet,  occur  below,  above  it  are  three  other  seams,  two  of 


124 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


which,  the  Peacock  and  Graden,  are  being  developed.  A section 
of  the  mine  beginning  from  below  upwards  is  as  follows  : 

1.  Massive  basal  sandstone  in  bed  of  creek  with  fucoidal 
fossils. 

2.  Coal,  two  feet ; 

3.  Sandstone,  ten  feet ; 

4.  Coal,  eighteen  inches  ; 

5.  Sandstone,  eighteen  feet ; 

6.  Porter  coal  seam,  three  feet  six  inches  ; 

7.  Sandstone,  ten  feet ; 

8.  Coal,  two  feet ; 

9.  Sandstone,  ten  feet ; 

10.  Peacock  coal,  five  feet; 

1 1.  Sandstone  and  shale,  seventy-five  feet; 

12.  Graden  coal,  four  feet; 

13.  Sandstone,  100  feet,  forming  the  top  of  the  hill. 

In  the  last  foot  of  the  Peacock  there  is  about  an  inch  of  shale 
and  a little  bone  in  the  Graden,  these  seams  are  only  partially 
developed. 


THE  SAN  JUAN  COAL  MINE. 

This  mine  is  located  near  the  junction  of  Lightner  creek  and 
the  Animas.  The  openings  are  near  the  summit  of  the  great 
hogback,  which  overhangs  the  town  of  Durango  on  the  west, 
and  the  works,  with  their  long  gravity  tramway,  are  a conspic- 
uous object  from  the  city,  perched,  as  they  are,  near  the  top  of 
the  steep  slope  of  the  hill,  600  feet  above  the  river.  The  seams 
are  apparently  a continuation  of  those  we  have  described  at  the 
Porter  mine.  A self-acting  gravity  tramway,  2,600  feet  long, 
brings  down  the  coal  from  the  mine  and  discharges  it  at  the  base 
of  the  hill  near  the  coke  ovens,  and  not  far  from  the  Rio  Grande 
railway.  The  tunnel,  the  opening  of  which  we  see  from  the 
town,  cuts  entirely  through  the  top  of  the  hogback,  from  day- 
light to  daylight,  following  the  dip  of  the  seam,  which  is  about 
nine  feet  in  100.  The  length  of  this  main  tunnel  is  1,400  feet. 
From  this,  side  tunnels  are  run  off,  varying  from  300  to  500  feet 
in  length.  The  mine  is  worked  by  the  “ room  and  pillar”  system, 
instead  of  the  “ Long-wall,”  which  is  usually  adopted  for  small 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  125 

seams.  The  tunnels  and  rooms  are  of  necessity  low,  owing  to 
the  narrowness  of  the  seam,  which  is  but  four  feet  thick.  The 
coal  is  of  a superior  quality,  makes  excellent  coke,  and  supplies 
large  proportion  of  the  local  trade  with  coal  for  domestic  and 
other  purposes.  The  roof  of  the  coal  seam  is  of  shale,  with 
sandstone  above  it.  The  dip  is  from  three  to  four  degrees  to  the 
south.  The  present  advantage  of  this  mine  is  its  proximity  to 
the  city  and  railroad.  The  capacity  is  about  200  tons  per  day, 
though  at  present  they  are  taking  out  100  tons.  There  is  no 
fire  damp  in  this  mine,  as  the  coal  is  high  above  water  level  and 
the  seams  are  well  exposed  to  the  air,  where  they  outcrop  on 
both  sides  of  the  hogback. 

There  are  some  three  or  four  other  coal  seams  on  the  prop- 
erty, as  at  the  Porter,  which  are  not  at  present  developed.  In 
1885  the  Inspector’s  report  gives  3,500  tons  as  the  product  for 
that  year. 

In  the  valley  below  near  the  discharging  point  of  this  mine 
is  a small  coking  plant  of  a dozen  beehive  ovens  for  the  use  of 
the  local  smelter.  The  Porter,  San  Juan  and  other  mines  of  this 
district  send  some  of  their  coal  to  be  coked,  at  this  plant,  and  the 
results  appear  to  show  that  a coke  of  superior  quality  is  to  be 
obtained  from  the  coals  of  this  region.  In  appearance  the  coke 
is  bright  and  remarkably  firm  for  Colorado  coke.  We  predict 
that  it  will  be  a favorite  in  the  market,  and  will  have  a wide  in- 
stead of  a restricted  local  use. 

CARBONERO  COAL  MINE. 

This  mine  is  located  two  miles  south  of  Durango,  along  the  Rio 
Grande  railway,  and  close  to  the  bank  of  the  Animas  river.  The 
openings  are  upon  what  used  to  be  called  the  great  mammoth 
seam,  from  a false  impression  that  the  body  of  coal  formed  one 
enormous  seam,  eighty  to  ninety  feet  thick.  This  great  body  of 
coal,  however,  rather  consists  of  a number  of  separate  seams, 
which,  at  this  point,  come  very  close  together,  the  thickest  of 
them  not  being  more  than  seven  feet.  These  seams  are  separated 
from  one  another  by  numerous  narrow  belts  of  shale,  bone  and 
sandstone.  The  strata  seams  are  uptilted  to  thirty  or  thirty-five 
degrees,  and  the  main  tunnel  cuts  through  all  the  various  seams 


126 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


across  the  angle  of  dip,  a complete  section  being  thus  afforded,, 
of  which  the  inspector  gives  an  accurate  description  from  careful 
measurements  in  his  report  of  1886. 

1.  At  the  base  of  the  series  of  seams  is  a floor  of  sandstone 
100  feet  thick. 

2.  On  this  rests  five  feet  of  coal. 

3.  150  feet  of  sandstones  and  two  feet  of  coal. 

This  lower  group  may  correspond  to  that  at  the  Porter  and 
San  Juan  mines. 

4.  Then  fifty  feet  of  sandstone. 

5.  Twenty-one  seams  of  coal  from  a few  inches  to  seven  feet 
in  thickness,  separated  from  one  another  by  seams  of  shale,  bone 
or  sandstone  from  a few  inches  to  three  feet  thick,  while  about 
the  center  of  the  group  a belt  of  sandstone  six  feet  thick  occurs. 
Of  these  twenty- one  seams  about  six  are  workable,  being  from 
four  to  seven  feet  thick,  the  seven  foot  seam  is  near  the  base  of 
this  upper  series.  The  other  seams  are  respectively  five  feet,  six 
feet,  four  feet,  six  inches,  five  feet,  six  feet.  The  cap  is  of  sand- 
stone fifty  feet  thick.  Thus  this  upper  group  gives  us  seventy- 
five  feet  of  coal,  and  if  we  add  to  it  the  lower  group  we  have  a 
sum  total  of  eighty-three  feet. 

This  coal  gives  off  a great  amount  of  explosive  gas,  probably 
owing  to  its  being  so  near  to  water  level,  for  the  same  seams 
higher  up  in  the  hogback  at  the  La  Plata  mine  are  quite  free 
from  it,  proof  of  which  is  given  by  the  fact  that  some  old  work- 
ings at  the  La  Plata,  though  lying  idle  for  years  show  no  signs  of 
it.  In  our  examination  of  the  Carbonero  which  was  made  under 
considerable  difficulties  owing  to  the  suspension  of  work  for  some 
time,  we  noticed  in  the  water  that  covered  the  track,  bubbles  of 
gas  constantly  arising,  from  which  it  is  probable  that  the  source 
of  the  gas  is  in  the  floor  of  the  seam.  A powerful  current  of  air 
has  to  be  kept  up  to  counteract  this  gas  and  render  the  develop- 
ment safe.  The  coal  of  this  mine  when  taken  from  individual 
seams  is  of  good  quality  and  yields  excellent  coke,  but  if  the 
whole  body  of  coal  is  worked  together  a great  amount  of  bone 
and  shale  is  unavoidable  mixed  with  it.  A main  advantage  of 
this  mine  is  its  situation  on  the  line  of  the  Rio  Grande  railway. 

In  1885  the  Inspector’s  report  shows  that  for  that  year  it  was 
the  largest  producer  in  the  district,  its  output  being  5,900  tons. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


127 


The  coal  is  softer  than  that  of  the  Porter  and  San  Juan.  The 
softness  of  this  great  body  of  coal  as  compared  with  the  sur- 
rounding sandstones  has  caused  it  to  yield  more  readily  to  ero- 
sion, and  the  result  is  a little  valley  in  the  hogback  which  can  be 
followed  for  miles  with  a wall  of  coal  outcrops  on  one  side  and  a 
sloping  sand  floor  on  the  other.  We  might  follow  this  valley  for 
five  miles,  noticing  on  the  way  the  individual  seams  now  coming 
together  and  again  standing  apart  until  we  reach  the  next  impor- 
tant mine  on  this  belt. 

THE  LA  PLATA  COAL  MINES. 

These  mines  are  located  on  both  the  Carbonero  and  Porter 
belts,  but  at  a higher  point  above  the  water  level.  They  are  in  the 
great  hogback,  about  three  miles  in  a direct  line  from  Durango, 
and  about  six  by  the  present  wagon  road. 

The  seams  of  the  belt  have  here  separated  into  more  indi- 
vidual relations,  being  sometimes  many  feet  apart,  and  so  can  be 
worked  singly  without  any  great  admixture  of  shale  from  too 
numerous  partings.  Two  of  the  large  main  bodies,  embracing  in 
themselves  some  of  the  smaller  seams,  have,  however,  several 
partings,  but  distinct  enough  and  with  sufficiently  large  bodies 
of  pure  coal  between  them  to  allow  of  working  them  free  from 
the  partings.  These  bodies  are  from  fifteen  to  twenty  feet  thick, 
but  the  lower  portion  of  them  is  generally  too  much  split  up  by 
shale  to  be  worked  profitably.  The  belts  upon  which  this  mine  is 
opened  appear  to  embrace  most  of  the  seams  known  to  exist  in 
the  Durango  district,  both  those  of  the  lower  or  Porter  belt,  and 
those  of  the  upper  or  Carbonero.  This  mine  is,  consequently,  a 
comprehensive  one.  The  tunnel,  as  it  pierces  both  groupst 
encounters  a seam  at  the  end  very  like  that  of  the  San  Juan  in 
size,  character  and  quality.  The  greater  size  of  the  coal  bodies 
in  this  mine,  as  compared  with  those  in  the  mines  on  the  smaller 
seam  group,  allows  more  roomy  and  easy  development  and 
cheaper  mining.  The  other  mines  have  some  advantages  in  near, 
ness  to  the  town  or  to  the  railroad  track,  but  a branch  line  is  con- 
templated from  the  La  Plata  to  the  Rio  Grande  track  three  miles 
distant. 

The  amount  of  coal  on  this  property  is  enormous  ; it  is  also 
a coking  coal.  The  coal  seams  are  traceable  the  length  and 


128 


GEOLOGY  OF  COL  OF  A L>0  COAL  FIELDS. 


breadth  of  the  property.  An  outcrop  of  the  belt  in  a ravine 
about  half  a mile  east  along  the  hogback  shows  a seam  of  coal 
twelve  feet  thick  with  only  two  partings,  this  coal  appears  to  be 
hard  and  of  a semi-anthracitic  character.  It  was  not  sufficiently 
developed  to  take  samples  of  it,  but  I was  assured  that  it  would 
not  coke ; such  a change  in  so  short  a distance  in  the  quality  of 
the  coal  from  coking  to  non-coking  is  remarkable.  The  redness 
of  some  of  the  sandstones  near  this  coal  suggests  that  this  change 
may  be  the  result  of  local  combustion  at  some  early  date. 

The  openings  on  this  young  mine  consist  of  a tunnel  which 
has  so  far  reached  116  feet  but  has  in  that  distance  cut  through 
four  important  bodies  of  coal,  three  of  which  have  been  named 
respectively  the  Peacock,  the  Jumbo,  and  the  Fairmount,  all  large 
bodies,  while  at  the  end  of  the  tunnel  a small  seam  of  hard  and 
very  good  coal  is  found,  which,  from  its  apparent  correspondence 
with  the  Porter  seam  is  called  the  Porter  La  Plata,  or  tunnel 
number  three  seam.  As  the  tunnel  is  carried  further,  they  will 
strike  some  other  seams  of  the  lower  group,  one  certainly  five 
feet  thick  which  lies  immediately  upon  the  basal  “ fucoidal  ” 
sandstone  composing  the  floor  of  the  coal  and  the  massive  cap  of 
the  hogback.  They  intend  to  develop  this  mine  by  the  Long- 
wall  system,  an  unusual  one  for  Colorado  for  seams  of  so  large  a 
size.  The  present  main  tunnel  is  high  and  roomy  with  a broad 
gauge  track  adapted  to  connect  with  the  projected  branch  rail- 
road. The  company  is  the  La  Plata  Coal  Company  of  Durango, 
managed  by  Mr.  F.  O.  Blake  of  Durango  and  Mr.  Atkins  of  the 
Colorado  Savings  Bank  of  Denver. 

The  following  is  a description  of  the  seams  encountered  in  the 
tunnel  beginning  from  the  entrance : 


JUMBO  SEAM  (OR  TUNNEL  NO.  I SEAM). 


This  seam  is  fifteen  feet  thick. 
Solid  coal  next  to  roof  . . 

Shale  parting 

Solid  coal 

Shale  parting 

Solid  coal 


. 5 feet 


3 feet  6 inches 


3 feet  6 inches 
i foot 


8 inches 


Workable  total 


. . 12  feet 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


29 


Below  this  are  some  six  feet  of  small  seams  and  partings 
which  are  not  workable.  The  coal  of  this  seam  is  rather  harder 
than  that  of  the  others. 

FAIRMOUNT  SEAM  (OR  TUNNEL  NO.  2 SEAM). 

This  seam,  a few  feet  below  the  last,  is  about  twenty  feet 
thick. 


Solid  coal  next  to  roof 

Shale  parting 

Coal 

Shale  parting 

Coal 

Parting 

Coal 

4 feet 

3 inches 

2 feet 

2 inches 

4 feet  8 inches 

8 inches 

3 feet 

Workable  total 

13  feet  8 inches 

Below  this,  also,  are  some  seams  and  partings  not  workable 
at  this  point,  but  at  the  old  abandoned  tunnels  they  join,  showing 
workable  size  and  less  shale. 

PORTER-LA  PLATA  SEAM  (OR  TUNNEL  NUMBER  3 SEAM.) 

Seventy-two  feet  from  the  last  near  the  end  of  the  tunnel  is 
four  feet  six  inches, thick  of  nearly  clean  coal. 

Solid  coal  next  to  roof I foot 


Clay  parting  

1 inch 

Solid  coal 

3 feet  6 inches 

Total 

4 feet  6 inches 

DESCRIPTION  OF  FRONTISPIECE  PLATE  I. 

The  scene  depicted  in  the  frontispiece  is  from  the  top  of  the 
hogback  above  this  mine,  from  which  we  have  a splendid  pano- 
ramic view  of  the  region  for  hundreds  of  miles,  over  which  by 
the  color  and  relative  position  of  the  rocks  we  can  trace  as  in  a 
map  the  main  geological  features  and  structure  of  the  surround- 
ing country. 


i3o  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

In  the  distance  to  the  south  is  the  plateau  country  of  the  Ute 
reservation,  the  strata  of  which  are  mostly  of  Tertiary  age  com- 
posed of  rusty  sandstones  and  variegated  clays.  The  course  of 
the  Animas  may  be  traced  winding  like  a silver  thread  among 
the  mesas  and  passing  through  a gap  in  the  horizon.  To  the 
west,  a large  area  is  occupied  by  uplifted  Tertiary  and  Laramie- 
Cretaceous  coal-bearing  strata  underlaid  by  a thickness  of  about 
1,000  feet  of  Fox-hill  shales  which  are  easily  recognized  by  their 
drab  gray  color.  Through  this  hogback  country,  the  valley 
formed  by  the  erosion  of  the  great  Carbonero  coal  belt  is  clearly 
seen,  till  it  is  lost  in  the  distance  or  merges  in  the  horizontal 
strata  of  the  distant  Montezuma  valley,  where  in  our  picture  the 
sun  has  just  set.  At  the  base  of  the  steep  slope  of  Fox-hill 
shales  in  which  this  hogback  ends,  and  which,  as  we  have  ex- 
plained and  shown  by  the  section,  is  produced  by  a fault  of  about 
1,000  feet  fall,  begins  the  second  bench,  the  cap  of  which  is  formed 
by  gently  sloping  sandstones  containing  the  lower  and  thinner 
group  of  coal  seams,  worked  by  the  Shores,  San  Juan,  and  Por- 
ter mines.  This  too  in  turn  ends  in  a steep  slope  of  2,000  feet, 
above  the  river  and  city,  composed  of  Fox-hill  shale  capped  by 
the  basal  sandstone. 

Near  the  top  of  this  slope  the  San  Juan  mine  is  shown  with 
its  long  granite  tramway  carrying  the  coal  down  to  the  river-bed 
where  Lightner  creek  opens  into  the  Animas.  The  smoke  of  the 
smelter  of  the  San  Juan  Smelting  Company,  with  that  of  their 
coke  ovens,  is  seen  arising  from  the  bank  of  the  river.  Follow- 
ing up  Lightner  creek,  a ravine  in  the  hogback  leads  to  the 
Porter  mine.  A valley  of  erosion  about  a mile  wide  separates 
this  hogback  from  its  continuation  in  a series  of  castle-rocks  and 
tables,  the  sandstones  of  which  carry  the  same  coal  seams,  until 
finally  we  see  the  coal  strata  uplifted  against  the  snow-capped  La 
Plata  mountains  in  the  northwest. 

The  erosion  of  Junction  creek  cuts  off  the  coal  strata  on  the 
east  and  reveals  lower  strata,  consisting  on  top  of  the  Dakota 
group,  and  below  it,  the  Jurassic,  and  at  the  base  the  red  con- 
glomerate of  the  Trias.  This  hogback  is  again  cut  in  section  by 
the  beautiful  valley  of  the  Animas  river,  whose  waters  have  worn 
down  through  period  after  period  of  the  uplifted  strata  as  we 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  13 1 

ascend  the  canon,  till  finally  bedrock  granite  is  reached,  and 
further  on  we  find  the  whole  Palaeozoic  series  uplifted  against  the 
San  Juan  range  and  covered,  together  with  the  underlying  gran- 
ite by  the  mighty  lava  overflows  of  that  wonderful  and  pictur- 
esque region. 

The  town  of  Durango  is  seen  nestling  in  the  valley  of  the 
Animas,  strung  out  to  a great  distance  along  either  bank  of  the 
river,  and  above  it  on  the  north  rise  the  castle  rocks  with  their 
cliffs  of  shale,  which  are  sculptured  into  forms  noticed  by  every 
visitor. 

In  the  foreground  a portion  of  the  uplifted  bench  with  its 
basal-sandstone  cap,  100  or  more  feet  thick,  full  of  rusty  impres- 
sions of  fossil  Halymenites  sea  weeds  underlaid  by  the  Fox-hill 
shales  is  shown.  This  forms  the  great  sloping  floor  for  all  the 
coal  belts,  hence  the  first  valley  above  it  to  the  left  is  that  caused 
by  the  erosion  of  the  Carbonero  coal  belt,  which,  as  the  sketch 
indicates,  is  traceable  across  the  Animas  to  the  west,  and  along 
the  La  Plata  property  to  the  east.  Immediately  below  us  are  the 
workings  of  the  La  Plata  mine,  and  the  little  ravine  running 
south  along  the  course  of  the  creek  is  the  projected  line  of  the 
branch  railroad  to  the  main  Rio  Grande  track  whose  line  is  visi- 
ble in  the  middle  distance. 

The  next  valley  and  ridge  has  a stratum  of  fossil  shells  in  it 
but  no  coal  seams,  and  from  thence  to  the  next  purplish  ridge 
and  beyond,  no  more  coal  is  found,  as  the  strata  probably  belong  to 
an  upper  series  or  to  the  Tertiary.  The  accompanying  geological 
section  shows  the  leading  features  of  the  geology  of  the  district, 
and  the  small  side  sketch  the  workings  of  the  La  Plata  mine  and 
the  well  marked  outcrops  of  the  great  coal  seams. 

From  the  top  of  the  hogback  we  look  down  on  the  second 
bench  which  has  been  faulted  down,  and  can  trace  its  connection 
with  the  San  Juan  ridge  on  the  other  side  of  the  Animas.  In 
this  lower  bench  we  notice  the  City  Bank,  Black  Diamond,  and 
other  mines  on  the  San  Juan  small  seam;  as  these  mines  were 
not  working  at  the  time  of  our  visit  we  could  not  properly  exam- 
ine them. 

It  is  seldom  that  a geologist  has  an  opportunity  of  obtaining 
so  wide  a panoramic  view,  in  which  so  much  beautiful  scenery  is 
combined  with  such  an  easy  and  comprehensive  reading  of  the 


132 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


geological  features  of  the  country,  or  of  delineating  so  vast  a coal 
field  with  such  large  seams  of  excellent  quality. 

Analyses  of  coal  from  the  Durango  district  by  Professor  Geo. 
C.  Tilden. 

PORTER  MINES. 

PORTER  SEAM  NO.  I. 


Water  . . . 

63 

per  cent. 

Volatile  matter  . 

3470 

“ 

Fixed  carbon  . 

57-30 

“ 

Ash  (brown)  . . 

7-37 

100.00 

Sulphur  . . , 

0737 

PEACOCK  SEAM  NO.  2. 

per  cent. 

Water  . . . . 

• • • 2.49 

per  cent. 

Volatile  matter 

34-31 

(( 

Fixed  carbon  „ 

51-98 

“ 

Ash  (gray)  . . 

11.22 

IOO  OO 

Sulphur  . . . . 

1.68 

GRADEN  SEAM  NO.  3. 

per  cent. 

Water  .... 

2.94 

per  cent. 

Volatile  matter  . 

35  63 

“ 

Fixed  carbon  . 

50.65 

“ 

Ash  (light  yellow) 1078 

100.00 

Sulphur  . . . , 

i-53 

SAN  JUAN  MINE. 

per  cent. 

Water  .... 

1. 12 

per  cent. 

Volatile  matter  . 

37-30 

“ 

Fixed  carbon  . 

5469 

(( 

Ash  (light  brown) 6.89 

“ 

100.00 

“ 

Sulphur  . . . 

ii 

GEOLOGY  OF  COLORADO  COAL  FLELDS. 


133 


CARBONERO  MINE. 

Water 1.16  per  cent. 

Volatile  matter 34-33  “ 

Fixed  carbon 52.69  “ 

Ash  (gray) 1 1.82 

100.00 

Sulphur 1.22  “ 

THE  LA  PLATA  COAL  MINES. 

FAIRMOUNT  SEAM  (UPPER  SECTION  4 FEET  8 INCHES  THICK). 

Water.  1.2 1 per  cent. 

Volatile  matter 39.72  “ 

Fixed  carbon 51.02  “ 

Ash  (white) 8.05  “ 

10000 

FAIRMOUNT  SEAM. 

Lower  section  of  seam  four  feet  six  inches  thick. 

Water . 1.30  per  cent. 

Volatile  matter 39-7°  “ 

Fixed  carbon ...  54 .78  “ 

Ash  (light  red)  . . 4.22  “ 

100.00 

PORTER -LA  PLATA  SEAM  OR  TUNNELL  NO.  3. 

Water i.i  I per  cent. 

Volatile  matter 36.54  “ 

Fixed  carbon ...  5169  “ 

Ash 10.66 

1 00.00 


Sulphur 


1.450  per  cent. 


CHAPTER  VIII. 

Coal  Fields  of  Northwestern 
Colorado. 


CHAPTER  VIII. 

COAL  FIELDS  OF  NORTHWESTERN  COLORADO. 

GEOLOGICAL  NOTES  BY  THE  WAY. 

To  examine  this  district  we  took  the  Midland  railway  from 
Denver  via  Leadville  to  Glenwood.  The  Colorado  range,  the 
South  Park  and  Park  range  were  crossed  in  the  night,  and  early 
morning  found  us  at  Leadville.  The  train  took  us  a few  miles  up 
the  wide  Arkansas  valley,  and  then  turned  off  to  the  left  or  west- 
ward into  the  Sawatch  range  up  Lake  creek  canon.  The  Palae- 
ozoic quartzites  and  limestones  of  the  Leadville  series  are  seen  for 
a short  distance  up  the  Arkansas  valley  dipping  to  the  east,  off 
from  the  granite,  with  a few  mine  openings  in  them,  and  then  for 
many  miles  as  we  go  west  all  is  Sawatch  gray  granite,  showing 
evidence  of  former  glaciers  by  numerous  moraines,  polished  and 
striated  rocks  and  U shaped  canons,  until  we  cross  the  continental 
divide  and  go  down  into  the  valley  of  Frying-pan  Creek.  Near 
Lime  Creek  station  (Calcium)  we  meet  the  first  signs  of  sediment- 
ary rock  on  this  side  of  the  Sawatch  range ; they  are  Palaeozoic 
quartzites  and  limestones  dipping  to  the  west  off  from  the  granite 
axis,  at  an  angle  of  from  30  to  50  degrees  ; resting  on  these  is  a 
thickness  of  several  thousand  feet  of  gypsiferous  shales  belonging 
to  the  Upper  Carboniferous,  followed  above  by  fine  grained  red- 
sandstone  of  the  Triassic.  The  dip  of  these  is  at  first  steep  and  to 
the  west,  but  as  we  go  down  the  creek,  it  gradually  begins  to 
flatten  out,  and  as  we  approach  tne  Roaring  Fork  valley  the  dip 
again  rises  gently  in  a contrary  direction  to  the  east,  hence  a wide 
shallow  synclinal  trough  is  formed  between  Roaring  Fork  and 
the  Sawatch  range.  The  red  sandstone  being  in  many  places  of 
excellent  quality  is  extensively  quarried  for  building  stone,  not  far 
from  Aspen  Junction  along  the  Midland  route. 

Near  Aspen  Junction  the  hills  are  covered  with  a dark,  vesic- 
ular basalt  which  overwhelms  large  areas  of  this  district  and  is 
evidently  a surface  flow  of  comparatively  recent  date. 


138  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

As  we  go  north  down  the  Roaring  Fork  valley  in  the  direc- 
tion of  Glenwood,  the  east  banks  are  composed  of  red  Triassic 
sandstone  upwards  of  1,000  feet  thick,  dipping  east  45  degrees, 
and  west  on  the  other  bank,  forming  a steep  anticlinal  arch  the 
center  of  which  has  been  eroded  out  to  form  the  present  river 
beds  of  the  valley.  Beneath  this  some  pale  gray  shaly  beds 
appear  with  very  black  looking  bands  of  carbonaceous  looking 
material ; these  lower  beds  show  by  their  relation  to  the  Trias 
above  them,  that  they  belong  to  the  Upper  Carboniferous.  Some 
limestones  and  gypsum  occur  in  them. 

This  folded  anticlinal  and  synclinal  structure  is  due  to  the 
influence  of  the  Elk  mountains  on  the  west,  crushing  and  folding 
the  strata  intervening  between  their  eruptive  masses  and  the 
Sawatch  range.  One  of  their  majestic,  volcanic  peaks,  Mount 
Sopris,  appears  prominently  on  the  right,  to  the  southwest  of  us. 
Along  the  northern  and  western  base  of  this  mountain,  removed 
from  it  by  erosion  for  some  miles,  circle  the  coal  hogbacks  of  the 
Jerome  park  basin  among  which  are  the  coal  mines  of  Sunshine, 
Marion,  and  Spring  Gulch,  and  beyond  them  still  further  west, 
those  of  Coal  Basin.  The  little  town  of  Carbondale  is  located 
in  this  district  near  the  junction  of  Rock  Creek  with  the  Roaring 
Fork.  A few  miles  further  we  pass  through  Cardiff,  the  main 
outlet  and  coking  station  of  these  mines,  and  descend  into  the 
valley  of  the  Grand  river  where  the  pretty  town  of  Glenwood  is 
located  at  its  junction  with  the  Roaring,  Fork. 

GLENWOOD. 

The  Grand  river  just  east  of  the  town,  issues  from  a deep 
canon  in  Paloeozoic  rocks,  folded  over  Archoean  granite;  this 
granite  is  of  a reddish  color  containing  very  large  crystals  of 
orthoclase  feldspar,  often  six  inches  in  length.  The  dip  of  the 
sedimentary  rocks  some  way  up  the  canon  is  as  much  as  45 
degrees  to  the  west,  diminishing  gradually  to  25  degrees  near  the 
entrance ; the  strata  are  thrown  into  gentle  wavy  folds  accom- 
panied by  faults,  as  it  bends  down  from  the  steep  to  the  shallow 
dip  of  the  anticlinal  fold.  The  Grand  river  issues  from  this  canon 
in  the  Cottonwood  range,  (part  of  the  White  river  plateau),  as  a 
broad,  fast-flowing  stream  of  beautifully  clear  water.  After  its 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


*39 


exit  from  the  main  canon  and  union  with  the  Roaring  Fork  its 
course  is  through  a deep  valley  cutting  diagonally  across  the 
strike  of  all  the  sedimentary  series  shown  in  that  neighborhood ; 
in  this  way  we  have  exposures  of  the  Red-beds,  the  Dakota,  and 
the  Laramie  coal  beds,  the  strike  of  the  latter  running  approxi- 
mately northeast  and  southwest  parallel  to  the  course  of  the 
river.  At  Newcastle,  some  twenty  miles  north  of  Glenwood,  the 
river  takes  a sudden  bend  and  cuts  through  the  coal  hogbacks 
across  their  dip,  exposing  an  admirable  section  of  the  entire 
Laramie  group  with  its  many  contained  coal  seams.  From  the 
coal  hogbacks  it  emerges  on  to  a prairie  country  diversified  by 
plateaus  of  Tertiary  origin,  and  passes  out  of  sight  by  entering  a 
canon  in  the  Book  Cliff  plateau,  a series  of  lofty  table  lands  that 
bound  the  southwestern  and  northwestern  horizon. 

THE  HOT  SPRINGS. 

On  our  arrival  at  Glenwood  we  visited  the  far-famed  Hot 
Springs,  situated  on  the  shore,  banks,  and  even  in  the  bed  of  the 
Grand  river.  The  principal  ones  are  found  at  the  outlet  of  the 
canon  and  occur  at  intervals  of  a quarter  of  a mile  down  the 
river,  and  a half  a mile  up  the  river  in  the  canon.  The  largest 
and  most  utilized  are  on  the  north  bank  of  the  stream ; the 
springs  doubtless  issue  from  deep-seated  fissures  penetrating 
through  the  Paloeozoic  rocks  down  into  the  granite  beneath,  and 
emerge  through  the  overlying  pebbles  and  drift  of  the  river  as 
through  a seive,  which  disseminates  the  water  into  hundreds  of 
miniature  springs  bubbling  up  fiercely  in  the  center  of  pools 
varying  from  the  size  of  a saucer  to  many  yards  in  diameter. 
The  springs,  small  and  great,  throw  up  fountains  of  sand  into 
their  pools,  from  the  force  of  the  carbonic  acid  gas,  which 
violently  disturbs  the  surface  of  the  pools  in  escaping.  Some  of 
those  which  come  up  with  great  force  and  volume,  are  artificially 
enclosed  in  wide,  circular  reservoirs  of  red  sandstone.  Quite  a 
number  of  these  reservoirs  have  been  built  to  retain  the  water  for 
swimming  baths.  As  the  water  is  too  hot  for  bathing,  it  passes 
off  by  a sluice  into  a capacious  tank  or  swimming  bath  where  it 
is  cooled  to  a moderate  temperature.  The  water  in  the  hot  reser- 
voirs is  invisible  from  the  amount  of  steam  given  off,  but  through 


140 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


rifts  in  the  stream,  appears  of  a delicate  metallic  blue,  the  steam 
being  of  the  same  color,  though  fainter. 

The  dense  volume  of  steam  rising  day  and  night  from  these 
natural  caldrons,  is  a striking  spectacle  on  entering  the  valley, 
particularly  when  illuminated  by  moonlight.  The  temperature 
is  about  124  degrees  Fahrenheit.  Notwithstanding  this  great 
heat,  we  notice  a species  of  green  water-weed,  of  a low  order  of 
cryptogamia,  belonging  to  the  “ confervoideoe  ” family,  of  a dark 
olive-green,  ascending  from  below  in  long,  soft,  semi-gelatinous 
ribbons,  or  floating  free  on  the  surface  in  spongy  masses.  These 
plants  collect  around  them  much  of  the  solid  chemical  precipi- 
tates of  the  water,  such  as  soda,  lime,  salt,  and  are  used  by 
rheumatics  to  rub  themselves  down  with  after  a bath.  Carbonic 
acid  gas  is  copiously  discharged  from  these  springs,  and  in  part 
gives  the  force  to  the  bubbling  ebullitions.  Sulphuretted  hydro- 
gen is  also  present  and  gives  a taste  to  the  water,  but  not  to  a 
noxious  extent.  From  analysis  it  appears  that  the  main  com- 
ponents outside  of  these  two  gases  are  common  salt,  gypsum, 
carbonates  of  magnesia,  soda  and  lime,  and  silica. 

Besides  these  active  springs  there  are  evidences  over  quite  a 
large  area,  of  former  hot-spring  action,  now  extinct.  The  drift 
pebbles  forming  the  banks  of  the  stream  are  firmly  united  in  many 
places  into  a coarse  conglomerate  by  a calcareous  cement,  and 
by  calcareous  tufa  and  travertine,  mixed  with  iron  oxide  and 
other  incrustations,  due  to  hot  mineral  waters.  The  clays  of  the 
banks  above  the  springs  show  brilliant  colors  of  red,  purple  and 
maroon  tints,  from  oxidation  of  iron.  The  same  effects  resulting 
from  ancient  thermal  springs,  have  produced  the  wonderful  color- 
ing in  the  Yellowstone  canon  of  the  National  park.  A magnifi- 
cent $250,000  hotel  and  bath  house  of  red  sandstone  has  been 
constructed  by  the  Midland  railway  over  the  springs. 

The  hotel  is  to  be  equipped  with  most  elaborate  bathing 
accommodations  for  what  is  expected  to  become  a world-wide 
resort. 

From  this  principal  area  of  mammoth  and  dwarf  springs  we 
followed  the  railroad  track  up  the  canon  ; for  some  five  hundred 
yards  or  more  we  noticed  signs  of  springs,  active  or  dead,  some 
close  to  the  river,  others  on  the  banks,  and  some  on  the  cliffs 


GEOLOGY  OF  COL  OF  A VO  COAL  FIELDS. 


141 

above  the  river.  Those  in  the  river  are  bubbling  up,  and  in  most 
cases  are  surrounded  by  small  cisterns  of  masonry,  others  steam 
out  from  the  pebbles  of  the  bank,  the  steam  of  others  can  be  seen 
issuing  from  fissures  in  the  limestones  above  the  river,,  on  the 
walls  of  the  canon.  For  many  yards  we  observe  in  the  massive 
limestone  (which  appears  near  the  entrance  to  have  been  consid- 
erably disturbed  and  has  fallen  in  massive  blocks),  numerous  ver- 
tical fissures  on  jointing  planes  enlarged  at  various  points  by 
small  caves  and  holes,  coated  with  calcareous  tufa,  small  stalac- 
tites, and  other  evidences  of  former  hot-spring  action.  The 
extinct  fissures  in  the  cliff  above  appear  to  correspond  with  the 
line  of  active  springs  in  the  river  bed  below,  and  both  the  line  of 
fissures  and  the  springs  located  upon  them,  appear  to  cross  the 
river  and  coincide  on  either  bank. 

Just  at  the  entrance  of  the  canon  and  before  reaching  the 
massive  limestones  of  the  canon  walls,  we  pass  through  beds  of 
a shaly  character  belonging  to  the  Upper  Carboniferous,  the 
Lower  Carboniferous  limestones  dip  under  them  at  an  angle  of 
twenty  degrees.  These  limestones  are  exceedingly  massive  and 
homogeneous,  so  much  so,  that  it  is  hard  even  to  detect  signs  of 
lamination,  still  less  those  of  stratification,  and  as  it  is  cleaved  in 
a remarkable  way,  not  merely  by  the  deep  and  tolerably  wide 
fissures  of  ordinary  jointage  at  some  distance  apart,  but  in  places 
by  cleavage  lines,  so  close  together  as  almost  to  resemble  those 
of  slate,  we  are  apt  to  mistake  these  vertical  lines  of  cleavage  for 
the  real  lines- of  bedding.  Thus  we  might  at  first  sight  imagine 
the  strata  to  be  standing  on  edge  vertically,  instead  of  in  reality 
dipping  from  45  to  20  or  even  15  degrees  to  the  west,  as  is  clearly 
shown  further  up  the  canon  where  the  lines  of  bedding  are  dis- 
tinct. This  massive  limestone  from  its  characteristics  and  posi- 
tion relative  to  thin  bedded  drab  Silurian  limestones  below  it,  and 
the  Cambrian  quartzites  below  that,  which  rest  on  the  granite, 
we  assume  to  be  Lower  Carboniferous,  the  same  series  which  at 
Aspen  and  Leadville  contains  the  silver-lead  deposits. 

These  vertical  cleavage  fractures  have  been  enlarged  by  water, 
and  widened  into  narrow  caverns  encrusted  with  calcareous  tufa 
and  stalactites  of  aragonite.  There  are  some  twenty  or  thirty  of 
these  more  prominent  cave  fissures  within  a horizontal  distance  of 


I 42 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


500  yards  from  the  entrance  of  the  canon,  and  their  origin,  and 
relation  to  hot  springs,  is  clearly  shown  when  we  enter  the  Cave 
Bath  house. 

This  is  a bath  house  erected  over  one  of  the  hot  springs 
which  sends  up  its  steam  and  hot  air  through  a natural  fissure 
above  it,  which  by  this  action  has  been  eroded  and  enlarged  into 
a cave  large  enough  to  allow  a dozen  persons  to  sit  in  nature’s 
garb  upon  benches  cut  in  the  stone  sides,  and  there  be  thoroughly 
steamed  in  a natural  Russian  bath.  The  fissure  penetrating  the 
rock  is  about  fifty  feet  in  length,  and  doubtless  continues  on  as 
a mere  crack  for  an  indefinite  distance.  You  enter  the  cave  by  a 
sort  of  passage  way,  across  which  a flap  door  is  thrown,  the  heat 
appears  at  first  unendurable,  but  you  soon  become  accustomed 
to  it,  and  your  body  breaks  into  a profuse  prespiration.  The 
sides  of  the  cave  are  hollowed  out  here  and  there  into  smaller 
cavities,  and  these,  together  with  the  walls,  are  coated  with  traver- 
tine and  other  incrustations,  which  are  wet  and  dripping  with  the 
condensing  steam.  After  about  a quarter  of  an  hour  in  this 
V steam  bath,  you  emerge  from  the  cave,  take  a tepid  shower  bath, 
dress  quickly  and  walk  briskly  home,  well  wrapped,  with  a 
consciousness  that  every  possible  impurity  is  removed  from  the 
outer  pores  of  your  skin.  The  cave  has  been  and  is  still  being 
formed  by  the  ascending  steam  of  the  hot  springs  below,  of 
which,  probably,  at  one  time  it  was  also  the  channel  before  the 
erosion  of  the  river  had  reduced  the  position  of  the  springs  to  a 
lower  level  on  the  line  of  fissures. 

We  are  reminded  here  of  certain  theories  as  to  the  origin  and 
filling  of  fissure  veins ; we  see  heated  water  charged  with  mineral 
solutions,  such  as  lime,  soda  and  sulphur,  held  in  suspension  in 
the  vapor,  chemically  eroding  and  enlarging  a natural  fissure,  and 
depositing  upon  its  cooler  surface,  these  elements  by  precipita- 
tion, in  layer  upon  layer,  as  we  find  in  the  peculiar  ribbon- 
structure  arrangement  of  the  gangue  and  minerals  in  some  fissure 
veins. 

The  abandoned  caves  and  fissures  are,  many  of  them,  partially 
or  completly  filled  with  these  crystalline  deposits,  and  doubtless 
some  of  the  smaller  crevices  would  be  found  to  be  true  veins 
filled  with  ribbon-structure  calcite. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


*43 


PROBABLE  ORIGIN  OF  SPRINGS. 

The  remote  origin  of  the  hot  springs  is  doubtless  in  some 
fissure,  deep  enough  to  reach  the  buried  heat  of  the  earth,  ever 
increasing  as  great  depth  is  attained.  Such  a fissure  was  doubt- 
less formed  in  the  process  of  folding  up  and  elevating  the  moun- 
tains, the  evidence  of  such  dynamical  forces  together  with  the 
extrusion  of  volcanic  rock  in  a molten  condition,  are  peculiarly 
strong  in  all  this  region.  We  looked  for  evidence  of  such  a fault  or 
fissure  at  this  exact  point,  but  could  not  find  positive  proofs  of 
such  an  occurrence,  though  the  broken  up  appearance  of  the 
rocks,  and  the  parallel  cleavage  structure  at  the  entrance  of  the 
canon,  was  suggestive  of  the  proximity  of  some  great  faulting  or 
crushing  movement.  I am  inclined  to  think  that  the  springs 
occur  just  at  the  point  where  the  anticlinal  of  the  Roaring  Fol  k, 
which  we  have  already  noticed,  bends  down  into  a sharp  synclinal 
before  the  strata  are  again  uplifted  into  the  anticlinal  of  the  Cot- 
tonwood range,  such  a sharp  bend  would  be  likely  to  be  accom- 
panied by  faulting,  and  also  by  that  singular  compression,  of 
which  the  cleaved  limestones  at  the  entrance  of  the  canon  appear 
to  give  evidence. 

As  to  the  depth  of  the  fissure,  assuming  an  average  increase  ot 
heat  of  one  degree  for  every  50  feet,  we  should  have  the  present 
heat  of  the  springs  at  about  7,000  feet,  and  many  fault-fissures 
are  as  deep  and  deeper. 

Another  hypothesis  for  such  highly  heated  waters  may  be, 
that  in  the  folding  and  crumpling  of  the  rocks  to  which  this 
region  has  been  peculiarly  subjected,  great  mechanical  heat  was 
engendered,  which  still  lies  dormant  at  great  depths.  Surface 
water  penetrating  through  deep  fault  cracks  would  be  heated  and 
rise  to  the  surface  by  hydrostatic  pressure  as  well  as  by  force  of 
steam  and  the  carbonic  acid  gas  held  in  suspension. 

Lavas  again  of  modern  volcanoes  are  known  to  retain  their 
heat  at  some  distance  below  the  surface  for  an  enormous  time 
after  that  surface  has  cooled,  and  to  give  rise  to  such  phenomena 
as  geysers  or  hot  springs,  by  surface  water  percolating  through 
fissures  down  to  them.  We  observe  no  true  lavas,  ancient  or 
modern,  in  direct  connection  with  the  springs,  but  the  hills  around 


144  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

are  covered  with  comparatively  recent  basalt,  and  we  have  about 
fifteen  miles  from  this  center,  the  remains  of  a true  crater,  and  a 
very  recent  lava-flow  at  Dotsero,  which  we  shall  presently 
describe.  For  further  evidences  of  eruptive  action  on  a grand 
scale  we  have  but  to  look  at  the  magnificent  volcanic  cone  of 
Mount  Sopris,  whose  extrusion,  together  with  that  of  the  whole 
Elk  Mountain  range,  seems  to  have  exerted  a wide  influence  on 
the  dip  and  contortions  of  the  strata,  as  w^ll  as  on  the  partial 
metamorphism  of  the  rocks  of  the  region.  Mount  Sopris  and 
other  Elk  Mountain  peaks  are  vast  reservoirs  or  “ laccolites  ” of 
molten  rock  from  which  the  strata  that  once  folded  over  them,  as 
the  volcanic  mafter  was  intruded  into  them,  have  been  eroded  away, 
revealing  the  intense  volcanic  forces  that  have  been  active  in  this 
region.  So  as  hot  springs  are  generally  found  in  regions  of  vol- 
canic and  dynamical  disturbance,  we  are  not  surprised  to  find 
them  at  Glenwood  nor  should  we  be  surprised  to  meet  with  them 
at  various  other  points  in  the  Elk  Mountain  region 

GEOLOGY  OF  COTTONWOOD  CANON. 

Continuing  our  walk  up  the  Cottonwood  canon  we  pass  down 
(geologically)  from  the  massive  gray  Carboniferous  limestone  to 
thin  bedded  drab  limestones  of  the  Silurian  and  thence  to  Cambrian 
quartzites,  and  finally  through  Archcean  granite.  The  Palcezoic 
strata  rise  tier  upon  tier  to  a height  of  many  hundreds  of  feet, 
displaying  a considerable  thickness,  and  are  seen  to  gradually  arch 
over  the  top  of  the  mountain.  As  we  continue  onward,  the  faults 
become  greater  as  we  reach  the  axis  o.f  the  range,  and  at  times 
the  Paloezoic  rocks  are  uplifted  to  a great  height  on  a steep  fault- 
cliff  of  granite.  As  we  emerge  from  the  canon  on  the  east  side, 
the  structure  of  the  folds  is  similar  to  that  on  the  west,  gradually 
dying  out  on  the  flanks  and  giving  place  to  a bluff  country  of 
Upper  Carboniferous  strata  composed  of  variegated  gypsiferous 
shales  capped  by  the  red  beds  of  the  Jura-Trias  dipping  easterly. 
We  are  now  in  the  valley  of  the  Eagle  near  its  junction  with  the 
Grand,  and  stop  at  Dotsero  station,  our  object  being  to  examine 
the  remains  of  an  extinct  volcanic  vent  and  comparatively  recent 
lava  overflow  of  which  numerous  accounts  had  reached  us  when 
at  Glenwood. 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


145 


THE  DOTSERO  VOLCANIC  VENT. 

The  valley  of  the  Eagle  between  the  hills  is  from  one  to  two 
miles  in  width.  About  a mile  east  from  the  station  the  river  hugs 
the  south  edge  of  the  steep  face  of  the  hills.  At  this  point  a very 
black  looking  rock  covers  the  meadow  of  the  valley,  spread  out 
in  a fan  shape  like  a large  pancake  over  an  area  of  a square  mile. 
The  edge  of  the  cake  ends  abruptly  near  the  base  of  the  cliff 
forming  the  south  bank  of  the  river,  the  latter  cutting  through  it 
and  separating  it  from  the  cliff  beyond.  As  there  was  no  bridge 
we  waded  the  stream  and  ascended  the  opposite  bank.  The  bank 
proved  to  be  a rugged  cake  of  lava  over  fifty  feet  thick.  The 
central  portion  was  of  hard,  massive,  dark  gray  basalt  showing  a 
fluidal  structure  and  a few  small  steam  holes.  Above  this  were 
masses  of  scoria  piled  up  and  tumbled  along  in  chaotic  confusion 
like  furnace  slag.  Underneath  the  solid  portion  the  lava  was  also 
scoriaceous.  It  resembled  pictures  of  the  recent  lava  flows  of 
Mauna  Loa  or  Vesuvius.  The  blocks  of  “scoria”  were  as  vesi- 
cular as  honey  combs.  The  edges  of  the  little  circular  steam  holes 
were  as  fresh  and  sharp  as  if  the  flow  had  occurred  but  a week 
before,  and  were  not  filled  by  zeolites  or  amygdaloids  as  is  the 
case  generally  with  basaltic  flows  of  an  older  date.  The  surface 
of  a greater  part  of  the  flow  is  destitute  of  vegetation,  one  black, 
rugged  mass  of  slag  and  clinkers.  Toward  the  opposite  side  of 
the  valley  decomposition  has  allowed  a sparse  covering  of  grass 
and  sage  brush. 

I had  no  difficulty  in  tracing  the  flow  across  the  valley  to  the 
enhance  of  a narrow  ravine  in  the  hills.  Great  rugged  masses  of 
scoria  were  adhering  to  the  sides  of  the  ravine  as  though  a 
furnace  had  lately  poured  molten  iron  down  it.  Erosion  had 
removed  the  lower  portion  of  the  lava  and  bitten  into  the  sand- 
stones forming  the  bottom  of  the  ravine  Following  up  the  gulch 
for  about  a mile  into  the  hills,  the  lava  flow  became  thicker  and 
more  continuous,  and  appeared  eventually  to  issue  from  a huge 
semi-circular  bulging  mass  on  the  top  of  a hill  of  very 
steep,  smooth  outlines.  This  hill,  with  all  the  surrounding 
hilltops  at  this  level,  for  a circular  area  of  about  a mile 
in  diameter,  is  composed  or  covered  with  grey  “ lapilli,” 
little  fragments  of  scoria,  shale  and  red  sandstone,  from 


146 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


the  size  of  a pea  to  that  of  a hen’s  egg,  shot  up  by 
steam  from  the  throat  of  the  volcano,  and  falling  in  show- 
ers around  the  vent.  These  beds  of  “lapilli”  appear  to  be  ol 
considerable  thickness.  Near  the  top  of  the  hill  they  seem  to 
have  been  consolidated  into  a course  stratified  “breccia,”  tipped 
up  at  an  angle  of  5 or  10  degrees  on  either  side  of  the  great  mass 
of  lava,  as  though  the  latter  had  broken  through  this  portion  of 
the  crater  and  tilted  up  the  brecciated  sandstone  of  its  wall  in  its 
exit. 

Climbing  over  the  lava  mass,  I stood  on  the  top  of  the  hill 
and  looked  down  into  a perfect,  oval-shaped  crater,  the  bottom  of 
which  lay  between  600  and  800  feet  below  me.  The  walls  of  the 
crater  are  of  red  triassic  sandstone  between  500  and  800  feet  deep 
in  the  steeper  part,  while  from  the  top  of  the  lapilli-covered  hills, 
sloping  gradually  down  into  the  steep  throat  of  the  crater,  the 
height  was  over  1,000  feet;  the  crater  may  thus  be  said  to  be 
about  1 ,000  feet  deep. 

The  bottom  of  the  crater  is  oval  and  comparatively  flat,  dip- 
ping, however,  some  five  or  more  degrees  to  the  south,  that  is, 
towards  the  side  where  the  lava  seems  to  have  broken  through 
and  poured  out.  The  diameter  of  the  bottom  is  between  200 
and  300  yards,  the  surface  is  covered  with  debris  and  sage  brush, 
doubtless  overlying  a solid  plug  of  congealed  lava.  The  width 
of  the  crater  on  the  top  of  its  steeper  portion  is  about  500  yards. 
The  sides  of  the  throat  are  quite  steep,  having  an  inclination  of 
from  forty-five  to  seventy-five  degrees,  and  it  would  be  difficult 
to  climb  up  or  down.  I did  not  make  the  attempt  for  lack  of 
time.  There  is  no  natural  entrance  or  exit  to  the  crater,  it  is  a 
complete  cup. 

The  red  sandstone  strata  forming  the  walls  of  the  throat,  dip 
inwards,  at  an  angle  from  thirty  to  forty  degrees,  and  appear  to 
converge  towards  the  center  of  the  crater.  Time  only  allowed 
me  to  make  some  rapid  sketches  and  hurried  observations,  but 
from  what  I saw,  I think  the  following  may  be  the  history  of  this 
undoubtedly  true  crater  and  volcanic  vent. 

PROBABLE  HISTORY  OF  THE  VOLCANO. 

At  some  time,  probably  within  the  human  period,  eruptive 
forces  found  a vent  at  this  point  and  explosions  of  steam  blew 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


147 


out  a crater  hole  in  the  Upper  Carboniferous  and  Triassic  strata. 
That  the  action  was  explosive  I judge  from  the  great  quantities 
of  “ lapilli  ” and  continued  fragments  of  shale  and  sandstone  cover- 
ing the  surrounding  hills.  The  steam,  descending  as  water, 
worked  up  some  of  the  “lapilli into  a stratifed  breccia  around 
the  rim  of  the  crater.  When  the  explosive  energies  that  had 
filled  the  sky  with  clouds  of  steam,  ashes  and  “ lapilli  ” descend- 
ing in  showers  upon  the  surrounding  hills,  had  abated,  a volume 
of  lava  rose  in  the  throat  of  the  crater,  and  poured  out  over  the 
lip  on  the  south  side,  partly  breaking  through  the  crust  of  breccia 
and  tilting  it  up  as  it  passed  through  it.  From  the  lip  of  the 
crater  the  lava  poured  rapidly  down  the  steep  face  of  the  hill  and 
thence  through  the  narrow  gulch  into  the  open  valley,  where  it 
spread  out  as  a cake  over  the  meadows  and  on  to  the  river  which 
it  must  have  temporarily  dammed  back.  The  force  of  the  lava  was 
finally  checked  by  the  abrupt  cliff  forming  the  south  bank  of  the 
Eagle.  The  water  of  the  stream  may  also  have  arrested  its  pro- 
gress by  congealing  it.  Later  on,  the  river  cut  through  the  flow 
andre  sumed  its  course.  The  character  of  the  lava  sheet,  scoria- 
ceous  and  spongy  above  and  below,  massive  and  compact  in  the 
middle,  corresponds  with  what  is  observed  in  modern  lava  flows. 
The  surface  of  lava  in  contact  with  the  air  or  water,  gives  off  its 
imprisoned  steam  through  multitudes  of  little  steam-holes,  which 
reduces  the  surface  of  the  sheet  to  a rough,  spongy,  vesicular 
mass,  while  the  liquid  lava  continues  to  flow  on  below  until  it 
cools  in  a compact  body.  As  the  molten  stream  advances,  this 
spongy  surface  is  broken  up  into  clinkers  which  are  rolled  along 
on  the  top  of  the  liquid  stream,  and  falling  off  from  the  end  of  it, 
are  dragged  underneath  it,  and  all  together  are  piled  up  in  con- 
fused masses  where  there  is  any  check  or  obstacle  to  the  flow 
such  as  the  cliff  and  river  in  the  present  instance.  After  the  ex- 
trusion of  the  lava  the  red  sandstone  strata  collapsed  inward 
causing  the  converging  dip  alluded  to. 

Exactly  how  old  or  recent  may  be  the  date  of  this  eruption, 
it  is  not  easy  to  determine.  There  are  tall  fir  trees  growing  in 
the  crater,  and  thick  sage  brush  on  the  bottom.  I did  not  see 
any  signs  of  springs  or  emanations  of  gas  in  the  vicinity,  such  as 
are  common  in  recently  extinguished  volcanoes,  nor  are  volcanic 
rocks  particularly  abundant  in  the  immediate  neighborhood. 


148 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


The  occurrence  seems  rather  an  isolated  one.  This  interesting- 
locality  is  accessible  by  the  morning  train  of  the  Rio  Grande  rail- 
road between  Leadville  and  Glenwood.  The  lava  flow  is  just 
across  the  river  close  by  the  track,  but  the  crater  is  between  three 
and  four  miles  back  to  the  north  in  the  hills.  The  blue-gray 
“ lapilli  ” capping  the  hills  can  be  distinctly  seen  from  the  train 
and  mark  the  site  of  the  volcanic  vent. 

THE  NEWCASTLE  DISTRICT. 

Returning  to  Glenwood  we  followed  the  course  of  the  Grand 
down  through  a narrow  valley  in  a northwest  direction,  toward 
the  coal  mines  about  Newcastle.  Soon  after  leaving  Glenwood 
the  river  cuts  through  a great  thickness  of  red  Triassic  sandstones, 
then  through  the  sandstones  of  the  Dakota  Cretaceous,  and  (as 
we  near  Newcastle)  along  the  strike  of  the  Laramie  coal  group, 
which  forms  the  western  bank  of  the  stream  by  a very  steep  hog- 
back, 2,000  feet  high.  The  first  coal  opening  we  pass  on  the  side  of 
the  track  is  the  Pray  mine;  further  on  we  enter  the  valley  formed 
between  the  great  hogback  of  the  Laramie  on  the  west,  and  by  a 
lower  hogback  of  the  uppermost  member  of  the  Fox-hills  group 
on  the  east. 

Looking  up  the  face  of  the  almost  perpendicular  cliff  we 
notice  at  intervals  several  prominent  beds  of  sandstone,  with 
softer  shaly  beds  between  them,  the  outcrops  being  more  con- 
spicuous and  closer  together  towards  the  upper  500  feet  of  the 
cliff,  and  corresponding  to  some  seven  or  eight  different  coal 
seams,  dipping  with  the  hogback  about  50  degrees  to  the  west. 
About  1,000  feet  up  the  face  of  this  cliff,  the  tunnel  of  the  Elk 
Mountain  Fuel  Company  is  driven  through  the  hogback  a dis- 
tance of  1,000  feet,  exposing  in  its  course  a complete  section  of 
the  strata  and  of  the  principal  coal  seams  in  the  upper  portion  of 
the  hill.  Two  or  three  miles  more  brings  us  to  Newcastle,  a 
small  town  of  about  one  hundred  houses,  located  on  the  east 
bank  of  the  river  on  a flat  between  the  two  hogbacks.  The  rail- 
road spans  the  river  with  a fine  iron  bridge,  and  passes  through 
the  town  to  the  Newcastle  coal  mine,  located  about  half  a mile 
beyond  the  village,  at  a point  where  the  Grand  river  makes  a 
sharp  turn  to  the  west,  cutting  the  Laramie  hogback  in  two.  A 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 149 

complete  transverse  section  of  the  entire  Laramie  group  with  all 
its  enclosed  coal  beds  is  thus  exposed. 

The  coal  mines  are  in  prominent  view  from  the  village. 
Looking  toward  the  gap  we  see  three  openings  near  the  base  of 
the  hogback  a little  above  the  level  of  the  river,  and  three  more 
on  the  dip  of  the  strata  ; these  openings  at  short  intervals  from 
one  another,  represent  three  large  coal  seams.  The  first  and 
uppermost  seam,  “ D,”  is  five  feet  thick,  the  next  seam,  “E,”  or 
the  “Wheeler”  seam,  at  an  interval  of  100  feet  from  the  last,  is 
forty-five  feet  thick,  and  the  third  or  “ F ” seam,  eighteen  feet 
from  it,  is  sixteen  feet  thick.  There  are  several  other  seams 
above  and  below  these  of  more  or  less  workable  size,  but  these 
three  seams  are  the  only  ones  at  present  developed,  and  that  not 
to  a considerable  depth,  as  the  mines  are  in  their  infancy,  being 
but  a few  months  old;  of  the  six  tunnels  the  three  lower  ones 
average  about  500  feet  each  in  length. 

The  peculiarity  of  the  five  foot  “D”  seam,  is  the  extreme 
dryness  of  the  coal,  which  is  also  hard  and  compact,  showing 
but  little  signs  of  cleavage  or  “ butt  and  face  ” structure.  It  is 
on  this  account  a little  hard  to  work,  but  is  of  excellent  quality, 
not  slacking  on  exposure,  as  proved  by  fragments  of  coal  that 
have  lain  on  the  surface  for  years,  and  which  show  no  alteration 
or  influence  of  the  weather.  This  is  the  hardest  coal  in  this 
portion  of  the  hill. 

It  was  in  this  tunnel  that  a fatal  explosion  occurred  some  time 
ago,  which  is  generally  attributed  to  ignition  of  the  coal  dust  after 
a blast  had  gone  off,  this  dust  when  it  accumulates  being  highly 
inflammable  and  explosive.  To  prevent  similar  accidents,  a hose 
of  running  water  is  kept  in  constant  use  in  all  these  mines  to  lay 
and  moisten  the  dust  as  fast  as  formed.  That  the  dust  was  the 
cause  of  the  accident  is  clear  from  the  total  absence  of  any  gas  in 
the  mine. 

The  dip  of  the  coal  seam  is  about  fifty  degrees  to  the  south- 
west. The  tunnels  at  the  base  of  the  hill  pass  horizontally  into 
the  strata  along  the  strike,  stopes  being  worked  upward  with  a 
height  above  them  of  about  1,000  feet.  The  roof  of  the  seam  is 
of  massive  sandstone,  and  so  far  has  not  required  much  timbering. 

The  adjoining  great  Wheeler  “E”  seam,  forty-five  feet  thick, 
is  also  developed  by  a horizontal  tunnel.  Owing  to  the  great 


150 


GEOLOGY  OF  COLORADO  COAL  FLELDS. 


width  of  the  seam,  four  feet  of  coal  can  be  left  to  support  the  roof. 
The  coal  is  softer  than  in  the  five  foot  seam,  and  considering  the 
unusual  thickness,  remarkably  pure,  only  a few  thin  partings  of 
shale  being  found.  This  is  the  largest  seam  of  pure  coal  so  far 
discovered  in  Colorado. 

The  adjoining  seam  “ F,”  18  feet  from  it  and  16  feet  thick,  is 
of  very  similar  character.  There  are  some  slight  indications  of 
gas  in  these  two  seams  and  more  may  probably  be  encountered, 
when  greater  depth  under  the  mountain  is  attained.  In  the  pres- 
ent small  development  the  tunnels  give  good  enough  ventilation, 
which  will  be  increased  by  cross-cut  tunnels  uniting  the  main 
entries.  At  the  upper  workings  an  upcast  shaft  is  in  process  of 
construction,  which  will  be  supplied  with  a fan.  The  two  seams 
being  so  near,  the  tracks  from  their  tunnels  unite  in  a main  track 
running  out  on  to  a tipple,  from  which  the  coal  is  dumped  into 
the  cars  of  the  Midland  railway. 

From  the  lower  workings  we  ascend  to  the  upper  ones  on  the 
same  seam,  over  a double  incline  tramway  500  feet  in  length 
with  double  tracks,  on  which  ascend  and  descend  by  gravitation 
the  laden  and  empty  cars,  an  ingenious  contrivance  attached  to 
one  end  of  the  car,  automatically  setting  the  car  free  from  the 
guide  rope  the  moment  it  touches  the  platform  of  the  tipple,  thus 
dispensing  with  much  of  the  labor  involved  in  hooking  and 
unhooking  the  cars.  At  the  top  of  the  incline  the  three  seams 
are  again  well  exposed  by  an  open  cut,  and  by  short  develop- 
ments on  the  seams  themselves.  Above  the  coal  seams  we  notice 
a slight  depression  or  sag  in  the  hill,  where  the  shaly  or  more 
pliable  strata  immediately  overlying  the  coal  seams,  have  been 
puckered  into  a series  of  small  folds.  This  was  caused  by  fire  in 
the  coal  seams  at  some  unknown  period,  the  coal  having  been 
burnt  out  to  some  depth  below  the  surface,  causing  the  overlying 
strata,  by  collapsing,  to  be  thrown  into  the  folds  we  have  men- 
tioned. The  strata  in  the  neighborhood  of  the  coal  seams  have 
also  been  partially  metamorphosed  by  this  combustion  for  many 
miles  along  the  outcrop  and  for  several  hundred  feet  in  width 
In  the  coal  seams  in  these  upper  workings,  the  coal  near  the 
surface,  and  to  depths  not  yet  determined,  has  been  reduced  to  a 
species  of  anthracite.  Immediately  over  the  coal  is  a belt  of 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  151 

smut  a few  inches  thick,  then  pure  white  calcined  clay,  like  fire- 
brick, followed  by  red  and  yellow  calcined  shales.  The  surface 
all  along  the  strike  of  the  hogback  for  many  yards  on  either  side 
of  the  coal  seams  is  of  a red  color.  In  fact  both  in  the  New- 
castle reigion,  and  also  in  the  Sunshine  district,  some  twenty  miles 
distant,  the  presence  of  the  coal  beneath  can  often  be  traced  on 
the  surface  by  the  redness  of  the  strata.  We  were  told  that  in 
part  of  the  workings  of  the  Newcastle  mine  they  were  unable  to 
work,  owing  to  the  heat,  and,  although  there  is  no  present  sign 
of  active  combustion,  either  in  the  form  of  fire,  smoke,  or 
noxious  gases,  yet  some  two  or  three  miles  to  the  north,  along 
the  same  set  of  strata,  the  coal  is  actively  burning,  as  evinced  by 
clouds  of  vapor  issuing  from  the  ground,  which  can  be  seen  at  a 
considerable  distance.  There  is  a tradition  that  years  ago  old- 
timers  saw  the  area  now  worked  for  coal  similarly  ignited,  and 
if  so,  it  would  seem  that  the  fire  has  burnt  out  in  this  area  and 
continued  its  combustion  along  the  hogbacks,  more  in  a north- 
westerly direction.  We  have  at  present  no  evidence  to  prove 
how  deep  below  the  surface  the  fire  has  penetrated.  That  the 
heat  must  have  continued  slowly  for  a long  time,  seems  implied 
by  its  metamorphic  action  on  the  surrounding  strata,  and  the 
upper  portion  of  the  coal  seam,  such  processes  being  attributed 
usually  to  long  continued  slow  heat,  rather  than  to  violent  or 
active  combustion. 

About  one  hundred  feet  above  the  upper  workings  is  a red 
looking  mass  of  rock  resembling  a volcanic  breccia.  This  con- 
sists of  shale  and  sandstone,  metamorphosed  into  a hard  red 
jaspar  with  clinkers  here  and  there  coated  with  red  molten 
material,  the  cavities  in  the  breccia  being  lined  with  downy  crys- 
tals of  gypsum.  The  mass  was  very  much  like  a clinker  pile 
outside  an  iron  furnace.  On  moving  some  of  the  clinkers  we 
found  the  interior  of  the  mass  perceptibly  warm,  showing  the 
strong  latent  heat  still  existing  in  the  strata.  As  the  tunnels 
will  pass  under  the  hill  at  a depth  of  from  500  to  1,000  feet,  it  is 
probable  they  will  not  be  troubled  by  encountering  these  burnt 
or  still  burning  strata  until  they  near  the  surface  in  stoping 
upwards. 

We  followed  the  coal  strata  to  the  top  of  the  hogback  about 
2,000  feet  above  the  valley.  The  sandstones  were  reddened  in 


*52 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


the  neighborhood  of  the  coal  seam  to  the  very  summit.  Within 
a few  feet  of  the  top  Mr.  Thies  found  impressions  of  large  leaves 
of  a Laramie  type  in  the  sandstone.  These  were  proof  that  the 
horizon  of  the  coal  is  the  same  as  that  on  the  eastern  foothills. 

While  he  was  collecting  these  fossils  I climbed  to  the  top  from 
which  there  is  a sublime  view  of  the  surrounding  country,  an  idea 
of  which  I have  tried  to  represent  in  the  accompanying  panoramic 
sketch  (plate  XIII).  Looking  in  a southeast  direction,  immedi- 
ately below  us  is  the  valley  of  the  Grand  river,  which  flows 
between  the  great  coal  hogback  on  its  southwest  side,  and  a 
smaller  hogback  of  sandstone  on  the  east  side,  the  little  village  of 
Newcastle  lying  on  the  flat  near  the  center  of  the  valley.  The 
Grand  River  takes  a sudden  turn  toward  the  west,  cutting  through 
the  great  hogback,  near  the  point  where  the  Newcastle  mines 
beneath  us  are  located,  it  then  flows  for  many  miles  to  the  west, 
passing  out  of  sight  in  the  canon,  in  the  distant  Book  Cliffs.  The 
great  coal  hogback  is  the  most  striking  object  on  this  side,  rising 
abruptly  from  the  southwestern  bank  of  the  stream  in  a very 
steep  slope  to  a height  of  2,000  feet  above  the  river  bed.  Over 
the  crest  of  it,  we  see  a number  of  low  hogbacks  rising  in  tiers 
one  behind  the  other,  their  angle  of  dip  gradually  lessening  from 
forty-five  to  twenty  degrees,  until  the  strata  pass  under  a wide 
horizontal  plateau.  A valley  occupied  by  a little  stream  empty- 
ing into  the  Grand,  forms  the  dividing  line  between  the  uptilted 
hogbacks  and  the  horizontal  strata  of  the  plateau,  and  also  limits 
the  western  extension  of  the  Laramie  group  with  its  coal  bearing 
strata.  The  area  between  the  crest  of  the  hogback  and  the 
plateau,  is  called  Pinon  basin  from  the  heavy  growth  of  these 
dwarf  pines  upon  the  crests  of  the  thick  series  of  sandstones  of 
which  the  Laramie  group  in  this  section  is  largely  formed. 

The  strata  are  well  exposed  on  the  face  of  the  great  cliff  above 
the  river,  and  consist  of  a series  of  shales  and  sandstones.  The 
more  prominent  and  harder  belts  of  sandstone,  stand  out  in  relief 
from  the  softer  beds  of  shale,  and  in  many  cases  represent  the 
floor  and  roof  of  different  coal  seams.  The  shaly  portion  is  more 
toward  the  lower  part  of  the  cliff  while  the  sandstones  congregate 
toward  the  upper  part.  In  this  upper  section  occur  the  principal 
coal  seams,  some  seven  or  eight  in  number,  with  numerous  smaller 


GEOLOGICAL  SECTION  FROM  EAST  TO  WEST  DOWN  ELK  CREEK 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  153 

seams.  The  workings  of  the  Elk  Mountain  Fuel  Company  may 
be  seen  in  the  distance,  toward  the  upper  part  of  the  cliff,  cross- 
cutting and  developing  several  seams  by  the  Coal  Ridge  tunnel, 
nearly  1,000  feet  long,  which  emerges  on  the  Pinon  basin  side, 
letting  in  daylight  at  both  ends  The  sketch  will  give  an  idea  of 
the  great  thickness  of  the  Laramie  group  on  this  side  of  the 
mountains.  The  steep  cliff  of  the  hogback  represents  a vertical 
thickness  of  1,000  feet,  and  the  aggregate  thickness  of  the  hog- 
backs lying  in  sections  back  of  this  in  the  Pinon  basin,  2,000  feet, 
giving  a sum  of  3,000  feet  for  the  entire  group 

The  line  of  the  principal  coal  seams  as  developed  at  the  Coal 
Ridge  tunnel  will,  we  think,  if  protracted,  carry  the  coal  down 
near  to  the  base  of  the  hogback  and  cause  it  to  pass  under  the 
river  a little  above  the  town,  whence  it  is  continued  up  the  face  of 
the  hill  to  the  Newcastle  mines.  The  exact  outcrop  of  the  seams 
along  this  line  are  obscured  by  debris  and  vegetation. 

The  great  hogback  representing  the  northwestern  coal  field, 
after  leaving  the  valley  of  Newcastle,  swings  around  towards  the 
east  and  south,  in  the  direction  of  Rock  creek  and  the  Sunshine 
district  for  some  twenty  miles,  continued  on  by  the  coal  basin 
field  north  of  Sopris  peak,  thence  it  can  be  traced  up  Rock  creek 
towards  Gothic,  and  then  with  interruptions  by  the  eruptive 
masses  of  the  Elk  mountains  to  the  anthracite  and  coking  coal 
fields  around  Crested  Butte,  thence  up  Anthracite  and  Coal 
creeks  to  Irwin  and  beyond  until  it  merges  in  the  great  plateau 
of  the  Grand  Junction  and  Montrose  districts  Beyond  that 
again  it  can  be  traced  to  the  flanks  of  the  San  Juan  mountains 
near  Ouray,  that  range  separating  it  from  the  southwestern  field 
in  the  neighborhood  of  Durango. 

Turning  a little  to  the  left  of  our  drawing,  that  is  to  the  east 
and  southeast,  we  can  see  at  a glance  the  relative  position  of  the 
coal  group  to  the  periods  lower  in  the  geological  scale.  For 
east  t)f  the  little  hogback  behind  Newcastle,  is  a flat  valley, 
drained  by  the  waters  of  Elk  creek,  about  half  a mile  or  more  in 
width,  and  underlaid  by  the  marine  shales  of  the  Fox-hills  and 
Colorado  groups  of  the  Cretaceous,  dipping  at  a steep  angle  ; 
back  of  them  rise  the  sandstone  hogbacks  of  the  Dakota  Creta- 
ceous, and  behind  them  again  is  a great  thickness  of  some 


154 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


thousands  of  feet  of  red  Jurassic  and  Triassic  sandstones  and  lime- 
stones, which  in  turn  lean  upon  the  Palceozoic  limestones  and 
quartzites  of  the  Carboniferous,  Silurian  and  Cambrian  series, 
these  lastly  are  found  in  the  deep  canons  resting  upon  the 
Archean  granite  of  the  White  river  plateau  system.  Turning  to 
the  west,  we  observe  the  Laramie  group  passing  under  horizontal 
table  lands  of  Tertiary  origin,  which  comprise  also  the  strata  of 
Cactus  valley  and  a still  higher  group  of  the  Tertiary,  forming 
the  Book  Cliffs  in  the  far  distance.  Thus  is  the  section  complete 
from  lowest  Archean  to  highest  Tertiary. 

Could  we  from  our  standpoint  follow  the  course  of  the  coal 
hogback  to  the  northeast,  we  should  have  to  trace  it  for  fifty 
miles  curving  around  and  gradually  assuming  a northerly  route  in 
the  direction  of  Meeker  and  the  White  river  plateau  district,  where 
there  are  extensive  coal  fields.  It  is  cut  through  in  that  distance 
at  intervals  by  different  streams,  such  as  Rifle  and  Elk  cheeks. 
In  each  of  the  gaps  so  formed  the  cross-section  of  the  strata 
shows  more  or  less  coal  beds  of  a workable  size,  so  that  for  up- 
wards of  sixty  miles  along  this  hogback,  coal  may  profitably  be 
developed  as  railroads  and  markets  make  it  desirable. 

We  ascended  the  hogback  on  its  face  with  some  difficulty,  owing 
to  its  steepness  and  the  presence  of  a foot  of  snow.  We  descended 
on  the  dip  of  the  strata,  following  the  depressions  between  the 
massive  belts  of  sandstone,  caused  by  the  erosion  of  softer  shales 
or  coal  seams,  or  indicating  where  a coal  seam  had  been  burnt 
out.  On  arriving  at  the  base,  we  endeavored  to  obtain  a cross- 
section  of  the  strata  overlying  the  principal  coal  seams,  by  follow- 
ing the  course  of  the  Grand  river  which  cuts  through  the  group 
at  right  angles.  The  strata  consist  generally  of  some  2,000  feet 
of  drab  yellow  sandstone,  very  massive  and  heavily  bedded. 
Some  of  these  sandstones  showed  signs  of  fossil  vegetation  and 
cross  bedding,  and  others  of  a concretionary  tendency  on  a large 
scale.  The  shaly  element  in  this  portion  of  the  group  is  ih  the 
minority.  The  dip  appears  to  gradually  diminish  in  steepness 
from  50  degrees  at  the  coal  seams  down  to  25  degrees  near  the 
upper  portion  of  the  group.  The  strata  finally  pass  under  the 
soil  and  drift  of  the  valley  of  the  Grand.  Across  the  river  about 
half  a mile  distant,  horizontal  table  lands  set  in,  which  according 


coal-kith; e,  Newcastle,  Colorado. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


155 


tc  Mr.  Corryell,  are  formed  of  layers  of  conglomerate  covered  by 
basalt  No  coal  has  been  found  in  these  table  lands,  which  are 
doubtless  of  Tertiary  origin.  Mr.  P.  C.  Corryell,  the  foreman  of 
the  Newcastle  mines,  who  has  a thorough  scientific  knowledge  of 
the  region,  kindly  gave  me  the  following  detailed  section  of  the 
Laramie  group  at  Newcastle,  which  will  be  intelligible  by  reference 
to  the  section  on  the  plate. 

SECTION  OF  THE  LARAMIE  COAL  GROUP  AT  THE  NEWCASTLE 
MINES,  BY  P.  C.  CORRYELL. 

The  “A”  coal  seam  (three  feet)  is  the  uppermost  seam  of 
clean  coal  lying  between  ledges  of  massive  coarse-grained  sand- 
stone. The  sandstones  lying  above  this  seam  are  in  regular 
ledges,  alternating  with  clay  shale,  and  a black  Carbonaceous 
shale,  which  sometimes  passes  into  a coaly  substance.  The  sand- 
stones near  the  upper  series  are  more  conglomeratic,  and  finally 
pass  into  a true  conglomerate  of  pebbles,  with  some  shale  and 
marly  sandstones,  and  a few  fossil  traces  of  molluscs.  Below  the 
“A”  seam  is  a fine  grained  sandstone  with  small  partings  of  coal 
and  shale,  until  we  reach  the  “ B ” seam,  800  feet  below  “A.” 

The  “B”  seam  (four  feet  thick)  is  of  very  bright  clean  coal, 
the  hanging  wall  is  of  heavy  massive  sandstone  with  a foot  or  so 
of  shale  immediately  over  the  coal.  The  foot  wall  is  of  fireclay 
with  a ledge  of  calcareous  sandstone.  Below  this  are  several 
small  coal  seams,  each  a few  inches  thick,  interstratified  with 
sandstone  and  drab  sandy  shale,  for  a distance  of  fifty  feet.  Then 
follows  a series  of  heavy  bedded  sandstones  overlying  the  “ C ” 
seam.  The  distance  between  “ B ” and  “ C ” is  150  feet. 

The  “ C ” seam  (five  feet  thick)  is  of  hard  coal  resembling 
the  Sunshine  seam.  The  hanging  wall  is  shale  fifteen  inches 
thick,  above  which  are  eighteen  inches  of  coal  capped  by  the 
heavy  sandstones.  Below  the  seam  is  a footwall  of  shale  and  a 
bed  of  sandstone  fifteen  feet  thick,  followed  by  two  feet  of  coal, 
and  forty  feet  of  carbonaceous  shale  with  a number  of  small  coal 
seams  in  it  from  an  inch  to  twelve  inches  thick.  These  seams 
are  followed  by  successive  beds  of  sandstone  and  shale  with  a 
few  small  coal  seams  until  we  reach  the  line,  where  the  coal  has 
been  burnt  out,  forming  a little  gulch  about  300  feet  wide- 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


156 

Within  this  burnt  area  are  three  different  coal  seams  respectively 
one,  six  and  eight  feet  thick,  with  a belt  of  fossil  shells  forming 
the  hanging  wall  of  the  lava  seam.  In  places  where  the  strata 
have  not  been  much  burnt  the  shells  are  so  nearly  perfect  and  in 
such  abundance  that  the  outcrop  is  a complete  mass  of  them. 
These  shells  differ  from  the  lower  belt  of  shell  in  appearance  and 
size.  According  to  Dr.  White  of  Washington,  to  whom  I sub- 
mitted them  for  examination,  they  appear  to  be  fragments  of 
Ostrea  Corbiculo,  Anomia,  and  Goniobasis  subloevis,  all  Laramie 
types. 

The  strata  between  this  little  burnt  out  gulch  and  seam  “ D ” 
(five  feet  thick)  a distance  of  350  feet,  consists  of  heavy  ledges 
of  sandstone,  with  a few  small  seams  of  coal,  and  one  belt  of 
fossil  shells  about  two  feet  six  inches  thick,  between  which  and 
“D”  seam  laminated  sandstones  occur.  The  bed  over  “ D,” 
forming  its  roof,  is  a calcareous  sandstone  shown  in  fossil  ripple 
marks  and  tracks  of  worms  and  worm  borings  between  the 
partings. 

The  stratum  between  “ D ” seam  and  the  Wheeler  or  “ E ” seam 
(forty-five  feet  thick)  is  a black  carbonaceous  shale.  The  part- 
ing of  eighteen  feet  separating  the  Wheeler  seam  from  the  next 
seam“F”  (sixteen  feet)  is  a calcareous  shale  with  iron  pyrites 
and  sand. 

These  formations  might  be  divided  into  about  four  groups. 

The  great  thickness  of  the  Laramie  group  (3,000  feet),  the 
massive  sandstones  it  contains,  and  the  number  and  magnitude  of 
the  coal  seams  amounting  in  all  to  over  100  feet  of  coal,  are 
points  in  striking  contrast  with  the  development  of  the  same 
group  on  the  foothills  east  of  the  range,  which  rarely  attains  a 
thickness  of  2,000  feet,  with  the  shaly  element  predominating, 
and  where  the  coal  seams  are  rarely  more  than  five  or  six  in 
number.  Even  of  these  not  over  two  and  still  more  commonly 
but  one  is  of  workable  size,  averaging  eight  to  ten  feet.  Here, 
however,  we  have  two  seams  one  sixteen  the  other  forty-five  feet 
thick,  another  of  five  feet  close  to  it,  and  another  of  ten  feet  not 
far  off,  with  a half  a dozen  others  of  workable  size.  It  will  appear 
then  that  the  northwestern  coal  field  is  of  far  greater  importance 
than  the  eastern.  The  coal  also  shows  both  by  the  analyses  and 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  157 

the  practical  uses  to  which  it  is  put,  that  it  is  as  a rule  superior 
to  that  of  the  foothills.  The  regions  around  Trinidad  and  along 
the  foothills  have  some  advantage  in  facility  of  development 
because  of  the  horizontal  position  of  the  coal  beds  in  those 
regions,  but  the  disadvantages  of  the  steep  pitch  of  forty  to  fifty 
degrees  which  characterizes  the  coals  on  this  northwestern  side 
are  no  greater  than  those  of  many  of  our  coal  mines  on  the  east- 
ern slope  which  have  to  be  worked  in  highly  inclined  or  nearly 
vertical  seams.  On  the  other  hand,  the  advantages  of  nearness 
to  markets  and  the  accessibility  of  a great  number  of  railroads 
tell  at  present  in  favor  of  those  mines  nearer  the  great  plains.  It 
is  to  be  remembered,  however,  that  the  greater  part  of  the  States 
and  Territories  west  of  the  Rocky  Mountains  will  have  to  look 
to  these  northwestern  fields  for  their  coal. 

Analysis  of  coal  of  the  Newcastle  mines,  by  Prof.  George  C. 
Tilden. 


GRAND  RIVER  COAL  CO. 


THE  FIVE-FOOT-SIX  SEAM  (“d”). 


Water 

Volatile  matter  . . 
Fixed  Carbon  . . 
Ash  (light  brown) 


Sulphur 


2 98  per  cent. 
42.25 
50.09  “ 

4.68  “ 


100.00 

1.022 


THE  EIGHTEEN-FOOT  SEAM  (“  F”). 

Water 2.21  per  cent. 

Volatile  matter  . . 39-10  “ 

Fixed  carbon  ....  49-73  “ 

Ash  (white) 8.96  “ 

100.00 


Sulphur 


0.832 


158 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


THE  FORTY-FIVE-FOOT 

OR  WHEELER  SEAM  (“  E ”). 

Water 

Volatile  matter  .... 

41-58  “ 

Fixed  carbon  . . . . 

48.60  “ 

Ash  (brownish  white)  . 

7-97  “ 

100.00 

Sulphur 

COAL  RIDGE  MINES.  ELK  MOUNTAIN  FUEL  COMPANY. 

From  Newcastle  we  retraced  our  steps  two  or  three  miles  up 
the  Grand  river  to  the  workings  of  the  Elk  Mountain  Fuel  Com- 
pany. These  consist  of  the  aforementioned  tunnel  cutting 
through  the  top  of  the  hogback  about  1,000  feet  above  its  base. 
From  the  river  below  water  is  forced  by  a steam  engine  through 
a pipe  whose  length  is  5,200  feet,  over  1,000  of  which  is  up  the 
steep  slope  of  the  ridge  to  the  tunnel,  through  which  it  passes, 
and  supplies  water  to  the  mines  on  the  other  side  in  Pinon  basin, 
where  the  principal  devevelopments  are  being  carried  on.  The 
extreme  height  of  the  Coal-Ridge  hogback  at  this  point  is  1,800 
feet,  and  the  tunnel  is  located  about  1,000  feet  above  the  base. 
We  ascended  this  by  a zigzag  trail,  passing  on  our  way  over  sev- 
eral important  seams,  some  of  them  of  great  thickness,  one  being 
at  least  22  feet  thick,  and  when  developed  it  may  possibly  prove 
to  be  45  feet  thick  as  at  Newcastle,  to  whose  Wheeler  (“E”) 
seam  it  appears  to  correspond.  These  seams  lie  between  heavy 
beds  of  sandstone  which  occur  at  intervals  of  a few  hundred  feet 
with  beds  of  shale  or  thin  bedded  sandstone  between  them.  The 
tunnel  is  driven  in  about  325  feet  below  a notch  in  the  crest  of 
the  hill  from  both  directions,  is  1,300  feet  above  the  Grand  river, 
and  7,000  feet  above  sea  level.  It  is  wide  and  capacious,  eight 
feet  high,  seven  feet  wide  at  the  roof  and  eight  feet  wide  on  the 
floor.  The  rock  encountered  in  cutting  it  as  shown  in  the  accom- 
panying section,  was  shale  and  sandstone,  dipping  about  45 
degrees.  A few  fossil  shells  were  found  in  the  workings.  At 
the  time  of  our  visit,  there  were  a few  hundred  feet  near  the  mid- 
dle lacking  for  its  completion  ; we  have  since  heard  that  it  was 


Plate  XII. 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


!59 


finished  on  the  8th  of  May.  It  is  976  feet  in  length.  The  work, 
which  was  in  charge  of  Mr.  Ernest  Locke,  a former  student  of 
the  State  School  of  Mines,  came  together  from  both  ends  with- 
out the  slightest  variation.  When  the  connection  was  made,  a 
terrible  wind  swept  through,  blowing  the  workmen  along  and 
compelling  the  erection  of  banks  at  the  south  end  to  mitigate  its 
force.  Four  seams  of  coal  were  met  with  in  the  tunnel  which 
will  be  or  are  now  being  developed,  under  the  superintendence  of 
Mr.  Blount. 

Passing  through  the  tunnel  we  emerge  on  the  other  side,  and 
look  down  over  the  slope  of  the  great  hogback  into  Pinon  basin. 
A few  feet  below  the  mouth  of  the  tunnel  are  the  boarding  houses 
of  the  Company,  and  a trail  leads  off  to  the  south  along  the  back 
of  the  hogback  toward  Sulphur  gulch,  where  two  or  more  of  the 
seams  encountered  in  the  tunnel  outcrop  on  both  sides.  Open- 
ings have  been  made  on  these  to  connect  with  the  main  tunnel 
about  1,300  feet  distant,  by  a gentle  downward  grade.  There 
vre  other  gulches  adjacent  to  Sulphur  gulch  in  which  the  same 
.earns  similarly  outcrop,  they  could  all  be  worked  and  united 
with  the  main  tunnel  by  a tramway. 

The  two  seams  outcropping  in  Sulphur  gulch  about  200  feet 
apart,  average  five  feet  each  in  thickness,  both  carry  a very  super- 
Or  quality  of  coal,  one  of  them  quite  hard.  The  analyses  will 

v their  grade,  and  here  it  may  be  remarked  that  in  this  region 
quality  is  of  far  more  importance  than  quantity.  The  local  trade 
being  small,  this- coal  has  to  be  shipped,  and  must  command  the 
market  over  other  coals  in  order  to  pay ; thus  this  company, 
under  the  advice  of  Mr.  R.  C.  Hills,  has  gone  into  all  this  labor 
and  expense  of  developing  coal  on  the  top  of  a very  steep  hog  - 
back, simply  on  the  strength  of  finding  some  comparatively  small 
seams  of  very  superior  quality,  in  preference  to  developing  seams 
of  enormous  size  but  of  inferior  quality,  much  more  accessible 
near  the  base  of  the  hogback.  These  latter  they  keep  in  reserve 
for  future  years  when  more  railroads  and  near  markets  will  per- 
mit profitable  working.  But  little  timbering  is  necessary  in  these 
mines,  as  the  walls  are  generally  of  firm  or  heavy  bedded  sand- 
stone. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


160 


The  capacity  of  these  mines  taken  altogether  would  be  about 
5,000  tons  daily,  but  at  present  they  purpose  to  handle  only  600 
tons  by  their  single  tramway  leading  down  from  the  tunnel.  If 
the  tracks  were  doubled  they  could  handle  1,200  tons  daily. 
They  employ  150  men  at  present.  The  coal  will  be  sent  down 
by  the  tramway  from  the  tunnel  to  the  bottom  of  the  ridge,  and 
be  received  on  a side  track  connected  with  the  Midland  railway, 
about  a mile  distant.  The  Denver  & Rio  Grande,  whose  tracks 
lie  on  the  other  side  of  the  river,  would  also  receive  their  coal. 
Their  markets  would  be  principally  the  states  and  territories  on 
the  western  slope,  while  some  of  their  superior  coal  will  compete 
in  markets  nearer  the  Missouri  river. 

From  the  top  of  the  ridge  I took  another  panoramic  sketch, 
(see  plate  XIII)  which  shows  some  country  to  the  north  that  was 
obscured  in  the  one  taken  from  Newcastle.  The  geological  sec- 
tion accompanying  it,  was  taken  up  one  of  the  tributaries  of  Elk 
creek  a little  north  of  Newcastle,  and  shows  the  geological  rela- 
tions of  the  strata  in  the  vicinity  from  the  Archaean  granite 
mountains  on  the  east  to  the  Tertiary  plateau  on  the  west. 

ANALYSIS  OF  COAL  OF  COAL  RIDGE  (ELK  MOUNTAN  FUEL  CO.) 

[By  Professor  Tilden  ] 

SULPHUR  GULCH  MINE. 

Water 5.29  per  cent. 

Volatile  matter 40.70  “ 

Fixed  carbon 49  73  “ 

Ash  (light  brown) 4.28  “ 

100.00 

Sulphur  546 


SEAM  NOT  CUT  BY  MAIN  TUNNEL  AT  TIME  OF  VISIT. 


Water  . . . 
Volatile  . . 
Fixed  carbon 
Ash  (red)  . 


5.14  per  cent. 
40.14  “ 

5146  “ 

3.26  “ 


1 00.00 
0.580 


Sulphur 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


SUNSHINE  DISTRICT,  JEROME  PARK. 

We  returned  to  Glenwood,  and  next  day  in  company  with 
Mr.  Morgan,  superintendent  of  the  Grand  River  Coal  Mines,  went 
by  sleigh  to  Cardiff,  five  miles  south  of  Glenwood,  up  the  Roar- 
ing Fork.  This  is  the  central  outlet  and  point  of  delivery  for  the 
mines  of  Sunshine,  Marion  and  Spring-gulch  belonging  to  the 
Grand  River  Coal  and  Coke  Company,  it  is  also  the  coking  place 
for  the  coals  from  those  mines.  A long  line  of  coke  ovens  has 
been  built,  a hundred  of  which  are  in  active  use  and  another 
hundred  in  course  of  completion.  The  ovens  are  built  of  red 
sandstone  and  are  of  the  rectangular  arch  pattern  producing  both 
24  and  48  hour  coke.  A very  large  tipple  receives  the  coal  from 
the  mine  and  dumps  it  into  the  coke  larries  which  run  along  on 
top  of  the  ovens.  The  demand  for  the  coke  is  in  excess  of  the 
supply  at  present,  it  is  taken  principally  by  the  silver  smelting 
works  along  the  eastern  foothills  and  in  the  states  and  territories 
west  of  the  range. 

The  valley  of  the  Roaring-Fork  at  Cardiff  is  cut  out  of  a 
sharp  anticlinal  arch  in  the  red  beds.  The  red  rocks  on  the  east 
side  of  the  valley  dip  a few  degrees  to  the  east,  and  on  the 
opposite  side  they  are  vertical,  gradually  dipping  at  a steep  angle 
to  the  west.  As  the  Silurian  and  Paleozoic  series  to  the  east 
again  dip  west  off  from  the  Sawatch  range,  a synclinal  along 
Frying-pan  creek  must  occur  between  Roaring-Fork  and  the 
Sawatch  range,  followed  by  an  anticlinal.  This  is  but  the  begin- 
ning of  the  disturbances  caused  by  the  uplift  of  the  Elk  moun- 
tains which  we  find  so  powerfully  developed  as  we  approach  them. 
The  general  effect  is  to  crumple  up  the  strata  between  them  and 
the  Sawatch  range. 

From  Cardiff  the  coal  train  by  a branch  line  cuts  through  all 
the  sedimentary  beds  across  their  dip  and  shows  a good  section 
from  the  Trias  to  the  Laramie. 

First  we  pass  through  a great  thickness  of  Triassic  “ red-beds  ” 
standing  vertically  and  among  them  traces  of  eruptive  action  and 
remains  of  basaltic  overflows  of  very  vesicular  lava  which  must 
have  poured  out  on  the  surface.  Boulders  of  this  lava  we  find 
widely  strewn  over  the  whole  area,  and  sometimes  completely 


162 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


covering  the  surface  of  the  hills  and  valleys,  especially  the  Fox- 
hill  shales,  and  portions  of  the  Laramie  group. 

Next  comes  a little  valley  of  soft  variegated  Jurassic  strata 
followed  by  the  Dakota  sandstone  ridge  dipping  fifty  degrees  west. 
In  this  sandstone  ridge  a belt  three  feet  thick  of  blue  fireclay  is 
found  as  at  Golden,  which  has  been  successfully  used  for  lining 
the  coke  ovens  at  Cardiff. 

Next  to  the  Dakota  hogback  is  another  flat  valley  occupied 
by  the  soft  shales  of  the  Fox-hills  and  Colorado  cretaceous. 

Then  we  come  to  the  lofty  hogback  of  the  Laramie  coal  series 
dipping  forty-five  to  fifty  west.  We  pass  up  Sunshine  gulch 
through  a section  of  this,  which  shows  its  thickness  to  be  several 
thousand  feet.  The  bluffs  rise  2,000  feet  above  the  valley,  the 
strata  are  similar  to  those  at  Newcastle,  but  on  one  side  of  the 
creek  are  obscured  by  volcanic  matter. 

These  mines  have  been  in  operation  about  fifteen  months. 
The  development  is  principally  upon  one  seam  about  ten  feet 
thick  towards  the  middle  of  the  series.  The  coal  is  hard  and  has 
a semi-anthracitic  appearance,  and  is  much  prized  in  the  neighbor- 
hood, especially  for  domestic  purposes.  The  development  consists 
of  a tunnel,  driven  in  on  the  strike  of  the  coal  from  just  above 
the  level  of  the  creek  for  1,500  feet ; from  this  three  incline  slopes 
about  150  feet  deep  and  on  a dip  of  45  degrees,  decend  to  a lower 
tunnel,  driven  in  the  same  way  for  1,100  feet.  The  floor  and 
roof  on  either  side  the  seam  are  of  heavy  bedded  sandstone.  The 
lower  tunnel  being  below  the  bed  and  level  of  the  creek  is  wet, 
and  pumps  are  necessary.  Two  double  boiler  engines  for  hauling 
up  the  laden  cars  by  tail  rope  from  the  slopes  were  in  process  of 
erection.  The  coal  is  discharged  over  a tipple  into  the  cars  of 
the  Midland  railway,  whose  branch  line  runs  along  the  bottom  of 
the  gulch.  From  the  lower  level  the  mines  can  stope  upwards 
for  over  1 ,000  feet,  and  for  an  unknown  distance  north  and  south. 

Besides  this  ten  feet  Sunshine  seam,  three  other  workable 
seams  outcrop  on  this  property  in  a lower  series  800  to  1,000 
feet  below  the  upper  seam.  On  these  no  developments  of  impor- 
tance have  been  made. 

The  roof  of  one  of  these  seams  consists  of  a bed  two  to  three 
feet  thick  of  fossil  shells,  so  abundant  and  so  compressed  together 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  163 

that  the  rock  may  be  called  a shell-limestone.  According  to  Dr. 
White  they  are  species  of  Ostrea,  Corbicula  and  Unio.  Above  this 
shell  bed  are  the  ordinary  drab  yellow  sandstones,  below  it  are 
about  five  feet  of  lignitic  shale  capping  a coal  seam  four  feet  thick, 
separated  from  a still  lower  coal  seam  five  feet  thick,  by  about 
twenty  feet  of  thin  bedded  sandstone.  Below  these  coal  seams 
are  some  800  feet  of  sandstones  and  shales,  before  we  reach  the 
true  marine  Cretaceous  shales  of  the  Fox-hills  group.  In  the 
sandstone  between  the  two  seams  we  found  an  impression  of 
Halymenites,  and  also  part  of  a palm  or  a reed  with  a Carpolithes 
or  stone  fruit.  This  shell-bed  represents  a lake  or  body  of  water 
fringed  by  vegetation,  but  probably  not  far  above  the  sea  level, 
as  implied  by  the  Halymenites.  The  shells  are  of  fresh  or 
brackish  water  origin,  and  true  Laramie  types.  This  fossil-bed 
is  traceable  to  Marion  gulch  six  miles  south,  where  it  also  forms 
the  roof  of  one  of  their  coking  coal  seams,  and  upwards  of  thirty 
miles  to  the  north  we  found  fragments  of  the  same  shells  at  the 
foot  of  Coal  Ridge,  and  further  on  about  four  miles  we  have 
already  described  the  shell-beds  of  the  Newcastle  mines.  The 
lake  or  body  of  water  must  have  had  a length  of  at  least  thirty  or 
forty  miles  so  far  as  present  discoveries  show,  and  probably  a 
very  much  greater  extent. 


MARION  MINE. 

From  Sunshine  we  took  the  afternoon  coal  train  to  Marion. 
We  wound  around  several  headlands  of  the  Laramie  bluffs  and 
found  ourselves  suddenly  on  the  rim  of  Jerome  Park  basin,  lying 
far  below  us.  From  the  edge  of  the  basin  we  have  a magnificent 
view  of  Sopris  peak,  and  looking  up  the  deep  gorge  of  Crystal 
river  and  Avalanche  creek  (see  plate  XV)  we  observe  that  the 
Dakota  together  with  the  “ Red-beds  ” and  other  Mesozoic  strata 
curve  around  the  peak,  like  the  circling  walls  of  an  amphitheater, 
with  the  volcanic  dome  in  the  center.  The  dip  also  becomes 
very  steep  and  often  vertical,  as  if  the  strata  had  been  thrown 
back  on  all  sides,  as  the  monstrous  “ laccolite  ” arose  intrusively 
among  them. 

It  was  sunset  when  we  reached  the  mines,  but  before  darkness 


1 64  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

came  on  we  visited  a recently  opened  seam  of  hard  coal,  up  the 
Marion  gulch.  This  seam  is  supposed  to  correspond  to  the 
Sunshine  seam.  Owing  to  local  faulting  and  pinching,  it  showed 
at  first  only  a few  inches  on  the  surface,  but  at  ioo  feet  opened 
up  to  between  four  and  five  feet  in  thickness.  This  seam  is  a 
thousand  feet  above  the  lower  seams  worked  at  Marion,  and  as 
the  latter  correspond  to  a lower  series  of  seams  at  Sunshine,  as 
shown  by  the  fossil  shells  forming  the  roof,  it  is  probable  that 
this  new-found  seam  corresponds,  as  is  supposed,  to  the  upper 
Sunshine  seam. 

They  are  working  three  seams  of  coal,  one  six  feet  thick  of 
coking  coal ; another,  forty-five  inches  thick,  which  is  overlaid 
by  the  fossil  shell  bed,  and  separated  from  the  next,  which  is  four 
feet  six  inches  thick,  by  sixty  feet  of  sandstone  and  shale.  Fifty 
feet  of  sandstone  and  shale  is  again  followed  by  another  seam 
ten  feet  thick.  A seam  of  “bone”  two  feet  thick,  gradually 
diminishing  in  size,  comes  in  near  the  foot  wall  and  above  the 
last  foot  of  coal,  to  avoid  which  they  work  only  eight  feet  of  coal. 

The  developments  at  Marion  are  three  tunnels,  the  upper  one 
1,500  feet,  the  two  lower  4,000  feet  each.  The  coal  is  discharged 
from  the  upper  workings  by  a gravity  incline  tramway,  with  an 
automatic  arrangement  at  one  end  of  the  car  for  uncoupling  it, 
thence  over  the  tipple  to  the  railway  cars  below.  The  present 
workings  are  fifteen  months  old,  but  the  mine  had  previously 
been  worked  in  a small  way  to  get  coke  for  the  Aspen  smelters, 
and  a small  plant  of  a dozen  ovens  still  remains  on  the  ground. 
This  plant  is  now  being  increased  to  100  ovens. 

The  output  of  this  mine  is  250  to  300  tons  daily,  the  greater 
portion  of  which  is  turned  into  coke. 

SPRING  GULCH  MINE. 

From  Marion  we  walked  to  Spring  Gulch.  This  is,  in  many 
respects,  a counterpart  of  Marion.  Three  seams  occur  here 
named  respectively  “A,”  “ B ” and  “C  “A”  is  ten  feet,  “ B ” is 
six  feet  and  “C”  four  feet  thick.  “A”  is  the  lowest, “B”  is  forty- 
eight  feet  above  it,  and  “C”  fifty  feet  above  “B.” 

The  workings  on  the  south  side  of  the  gulch  are  two.  The 


I 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


165 


tunnel  entry  on  “A”  is  600  feet  long;  on  “ B”  2,500;  on  “C,”  with 
three  air  courses  to  the  surface,  1,200.  There  are  four  air  courses 
on  “ B ” to  the  surface  and  one  in  “A.”  The  length  of  one  slope 
incline  is  230  feet.  The  air  course  goes  from  “A”  to  the  surface 
entry. 

On  the  north  side  the  “A”  seam  is  not  worked.  On  “B” 
there  is  a tunnel  1,350  feet,  and  on  “C”  1,200  feet.  There  are 
three  air  courses  to  the  surface  on  “B.”  The  distance  of  upstop- 
ing  to  surface  is  75  to  1 50  feet,  according  to  the  slope  of  the 
.^mountain.  The  lower  rooms  are  1 50  feet  with  a thirty-foot  square 
butt,  and  eighteen-foot  pillar  between  each  room.  Rooms  are 
20  feet  wide  and  150  feet  long.  A steam  engine  is  employed, 
(double  reversible),  of  175  horse  power,  double  boiler.  The  roof 
is  good.  They  are  working  eight  feet  of  “A,”  four  feet  of  “C  ” 
and  six  feet  of  “ D,”  and  are  mining  coal  for  about  seventy-five 
cents  per  ton.  The  daily  output  is  250  tons,  which  could  be 
raised  to  500  tons,  lump  and  slack.  It  is  from  Sunshine  and 
Marion  that  the  company  derives  the  most  of  its  coke. 

Analyses  of  the  coal  of  the  Marion,  Sunshine,  and  Spring 
Gulch  mines,  Grand  River  Coal  and  Coke  Company,  by  Professor 
George  C.  Tilden. 


MARION,  SIX  FEET  SEAM. 


Water 

Volatile  matter 

Fixed  carbon  .....  

Ash  (light  brown) 

2.07  per  cent. 

• 3967  “ 

. 55.19  “ 

3-07  “ 

Sulphur 

100.00  “ 

0916  “ 

MARION  NO.  2. 

Water 

Volatile  matter 

Fixed  carbon 

Ash  (red) 

2.17  per  cent. 

■ 39  51  “ 

• 51-72  “ 

6.60  “ 

Sulphur 

100.00 

0.602  “ 

i66 


GEOLOGY  OF  COLORADO  COAL  LI  ELDS. 


MARION  NO.  3. 

Water 

Volatile  matter 

Fixed  carbon  < 

Ash  (brown) 


2.30  per  cent. 
3567  “ 

56.71  “ 

5.32  “ 


100.00 

Sulphur 1.521 

SUNSHINE,  SOUTH  SIDE,  LOWER  GANGWAY. 

Water 

Volatile  matter 

Fixed  carbon...... 

Ash  (light  brown) 

1 00.00 


3.40  per  cent. 
40.32  “ 

48.82  “ 

7.46  “ 


SPRING  GULCH,  FOUR-FOOT  SEAM. 


Water 

Volatile  matter. 
Fixed  Carbon.. 
Ash  (brown)  — 


1.26  per  cent. 

3695  “ 

54.89  “ 

6.90  “ 


100  00 

Sulphur 

SPRING  GULCH, 

NO.  2. 

Water 

Volatile  matter 

Fixed  carbon 

Ash  (brown) 

3463  “ 

57-24  “ 

6.36  “ 

100.00 

Sulphur 


1.018  per  cent. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


167 


THE  ROCK  CREEK  AND  COAL  BASIN  DISTRICT. 

From  the  Sunshine  and  Jerome  Park  district  we  had  intended 
working  one  way  along  the  course  of  Rock  Creek  in  the  direction 
of  Gothic  and  Crested  Butte  up  Coal  creek  and  Yule  creek  to 
coal  basin  and  the  marble  beds  through  one  of  the  most  interesting 
regions  in  Colorado,  but  were  unable  to  carry  out  our  plan  owing 
to  the  deep  snow.  It  is  in  this  direction  that  the  great  dynamical 
forces  of  the  Elk  mountains  show  themselves  most  violently. 
Along  Rock  creek  occur  most  remarkable  folds,  reversals  of  strata, 
and  great  faults,  while  the  action  of  the  heat  of  the  eruptive 
masses  and  that  mechanically  produced  by  overturning  is  manifest 
in  the  general  metamorphism  of  the  strata.  The  coal  is  frequently 
turned  into  anthracite  and  the  limestone  into  a beautiful  white 
and  blue  marble.  In  the  centre  of  the  axis  of  the  folds 
the  great  erruptive  laccolites  rear  their  massive  grey  domes 
and  roll  back  the  thick  sedimentary  strata  from  them  “as 
we  roll  back  the  coverlet  from  a pillow.”  As  important  coal  beds 
lie  in  this  section,  we  quote  Prof.  J.  S.  Newberry’s  account  of 
them. 


THE  COALS  OF  COAL  BASIN. 

BY  PROF.  J.  s.  NEWBERRY,  OF  COLUMBIA  SCHOOL  OF  MINKS,  N.  Y. 

About  40  miles  north  of  Crested  Butte  and  as  far  south  of 
Glenwood  Springs,  is  a district  which  has  been  called  Coal  Basin. 
This  is  one  of  the  most  peculiar  and  interesting  areas  which  I 
examined  in  Western  Colorado. 

It  is  evident  that  the  Laramie  coal  measures,  which  before 
were  nearly  all  horizontal,  were  once  at  this  point  raised  into  a 
dome  by  the  protusion  of  a mass  of  eruptive  rocks.  The  central 
portion  of  the  dome — doubtless  considerably  broken  up — has 
since  been  removed  by  erosion  to  form  a basin  five  miles  long  by 
three  miles  wide.  The  center  of  the  basin  is  excavated  deeply 
into  the  Colorado  shales,  the  middle  member  of  the  cretaceous 
system  of  this  region,  while  its  rim  is  formed  by  the  Laramie 
group  2,000  to  3,000  feet  in  thickness,  which  dip  away  from  the 
center  in  every  direction. 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS . 


1 68 


In  the  cliffs  which  border  the  basin  the  coal  seams  are  exposed 
and  accessible  in  many  places ; the  number  and  thickness  of  these 
seams  vary  considerably,  owing  to  local  changes,  and  to  the 
different  degrees  to  which  the  margin  has  been  eroded.  Where 
most  numerous  and  distinct  there  are  five  or  six  workable  seams, 
viz.,  three  above  the  lower  sandstone  ; one,  sometimes  two  or 
three,  above  the  middle  sandstone,  with  one  in  the  upper  sand- 
stone, and  several  small  seams  above.  At  the  west  end  of  the 
basin  the  lower  three  seams  are  closely  approximated  and  in  one 
place  run  together,  forming  what  may  be  regarded  as  a single 
seam  about  eighteen  feet  in  thickness.  Generally  the  three  seams 
are  separated  by  a few  feet  of  sandstone. 

The  eastern  rim  of  the  basin  is  formed  by  rocks  older  than 
the  Laramie,  viz:  the  Colorado  shales  and  Dakota  sandstones,  and 
below  these  the  Jurassic  and  Triassic  strata,  which  form  the  walls 
of  the  very  picturesque  canon  of  Coal  creek,  the  outlet  of  the 
basin.  These  walls  are  2,000  feet  in  height,  composed  chiefly 
of  purple  sandstones  weathered  into  all  sorts  of  fantastic  and 
imitative  shapes.  Rising  abrubtly  from  the  green  bottom  lands 
of  Crystal  river,  they  form  one  of  the  most  striking  and  beauti- 
ful portals  I have  ever  seen.  These  older  rocks  are  here  thrown 
up  by  a fault  or  sharp  fold,  which  crosses  Crystal  river  obliquely 
above  the  mouth  of  Coal  creek.  South  of  this  line  the  Laramie 
rocks  come  down  and  form  for  many  miles  the  walls  of  the  valley 
of  Crystal  river,  but  apparently  contain  no  very  good  or  accessi- 
ble coal.  Chair  Mountain  on  the  west  side  of  the  valley  con- 
tains some  anthracite,  but  it  is  too  much  broken  up  to  be  of  any 
value. 


MARBLE  BEDS. 

Twelve  miles  south  of  Coal  Basin,  Yule  creek  joins  Crystal 
river  from  the  southwest.  For  several  miles  the  valley  of  this 
stream  is  excavated  in  Palceozoic  limestones,  in  which  is  the  finest 
belt  of  marble  yet  discovered  in  the  United  States.  The  beds 
stand  nearly  verticle,  are  about  150  feet  in  thickness,  and  of  this 
nearly  one-half  is  pure  white,  and  would  be  classed  as  statuary 
marble.  Toward  the  top  of  the  deposit  are  some  layers  of  the 
purest,  loveliest  blue  marble  ever  seen. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


169 


The  coals  of  Coal  Basin  are  all  of  the  same  general  character, 
though  differing  considerably  among  themselves  in  the  degree  to 
which  this  character  is  developed ; that  is,  they  apparently  all 
belong  to  the  class  of  coking  coals,  and  are  generally  of  good 
quality,  containing  a small  amount  of  ash  and  sulphur. 

At  the  eastern  end  of  Coal  Basin  the  lowest  coal  seam  lies 
high  up  in  the  hills,  and  is  widely  separated  from  its  fellows.  It 
is  seven  feet  in  thickness,  looks  well,  but  is  peculiar  in  compo- 
sition and  inferior  in  quality  to  any  other  coal  observed  in  the 
basin,  since  it  contains  ten  per  cent,  of  ash  and  0.142  of  phospho- 
rus. Toward  the  west  end  of  the  basin  all  the  coal  seams  come 
down,  and  the  entire  section  of  the  Laramie  rocks  is  represented 
in  the  cliff  nearly  3,000  feet  in  height.  At  its  base  the  lowest 
three  seams  are  united  in  one,  or  closely  approximated,  giving 
eighteen  feet  of  coal  in  three  benches  or  distinct  seams.  They 
are  very  much  alike  in  appearance  and  quality,  containing  about 
one  per  cent,  of  sulphur,  and  0.0 n of  phosphorus.  A higher 
seam,  from  seven  to  eight  feet  in  thickness,  is  of  similar  character 
and  purity.  These  coals  make  excellent  coke,  and  as  they  under- 
lie an  area  of  many  thousand  acres,  are  capable  of  furnishing  an 
inexhaustible  supply  of  fuel  for  the  future  iron  and  lead  smelting 
of  Colorado 

The  coal  properties  on  the  south  and  west  sides  of  Coal 
Basin  belong  to  the  Colorado  Fuel  Company,  of  which  Mr.  T.  C. 
Osgood  is  president  ; those  on  the  north  side  of  the  basin  have 
been  acquired  by  the  Midland  Railroad  Company. 

To  connect  the  coal  mines  of  this  district  with  the  markets,  a 
railroad  is  being  constructed  down  the  valley  of  Crystal  river  to 
Carbondale,  where  it  will  join  the  D.  & R.  G.  and  Midland  roads. 

ANALYSES  OF  COAL  OF  COAL  BASIN. 

By  Prof.  J.  S.  Newberry  and  R.  C.  Hills. 

COAL  BASIN,  CLAIM  E. 

Moisture  1.089  per  cent. 

Volatile 36674  “ 

Fixed  carbon 52.956  “ 

Ash.; 8.981 

Sulphur 0.834 

Phosphorus 0.03859  “ 


170 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


COAL  BASIN,  CLAIM  H. 


Moisture 

Volatile  Matter  . 
Fixed  carbon  ... 

Ash 

Sulphur  

Phosphorus  


0.686  per  cent 
32.682  “ 

56.036 
10.140  “ 

0.454  “ 

0.142 


COAL  BASIN,  20  FOOT  SEAM,  OUTCROP. 


Moisture 

Volatile  matter 
Fixed  carbon.. 

Ash 

Sulphur  

Phosphorus  ... 


0.61 5 per  cent. 
23  532  “ 

67.030  “ 

7-993  “ 

0558  “ 

0.0 1 I “ 


COAL  BASIN,  20  FOOT  SEAM,  UPPER  BENCH. 

(R.  C.  Hills.) 


Moisture 

Volatile  matter 
Fixed  carbon  .. 
Ash 


1 9 per  cent. 
234  “ 

7i  1 “ 

3.6 


COAL  BASIN,  20  FOOT  SEAM,  MIDDLE  BENCH. 


(R.  C.  Hills.) 

Moisture  

Volatile  matter 

Fixed  carbon 

Ash 


1 . 1 per  cent. 

22.1  “ 

7 2.3  “ 

4 5 “ 


COAL  BASIN,  20  FOOT  SEAM,  LOWER  BENCH. 

[R.  C.  Hills.] 


Moisture 

Volatile  matter 
Fixed  carbon.. 
Ash 


1.9  per  cent. 
20.6  “ 

73-0  “ 

4-5  “ 


CHAPTER  IX. 

Coal  Fields  of  the  Crested 
Butte  Region. 


Chapter  IX. 

COAL  FIELDS  OF  THE  CRESTED  BUTTE  REGION, 
GUNNISON  COUNTY.* 

These  coal  fields  lie  in  the  heart  of  the  Elk  Mountains.  To 
reach  them  from  the  “ Plains,”  we  cross  three  parallel  ranges, 
the  Colorado  or  Front  range,  the  Park  range,  and  the  Sawatch 
range,  separated  from  one  another  by  trough-like  valleys  and 
parks.  On  the  northwest  of  the  Sawatch  range,  separated  from 
it  by  parks  and  valleys  of  sedimentary  rocks  we  encounter  a 
unique  group  of  plateaus,  domes  and  lofty  pyramids  of  eruptive 
rock,  coming  up  through  and  tossing  back  the  sedimentary  beds 
like  sheets  of  cloth  or  paper.  These  are  the  Elk  mountains. 
Within  a comparatively  small  area  in  this  region,  are  to  be  found 
the  most  striking  examples  of  volcanic  outbursts,  dykes,  and 
intrusive  beds  of  eruptive  rock,  accompanied  by  overturnings 
and  even  reversals  of  sedimentary  rocks,  with  wonderful  folds 
and  faults,  and  more  or  less  baking  and  metamorphism  of  the 
surrounding  strata. 

We  find  the  same  general  geological  section  as  on  the  east- 
ern plain  border,  reproduced  with  slight  modifications  on  this 
western  side  also ; and  though  the  strata  are  riddled  with  dykes 
baked  and  metamorphosed  in  places  almost  past  recognition,  we 
easily  detect  the  same  plant  fossils  and  marine  shells  which  we 
have  met  in  similar  relations  to  the  coal  on  the  plains. 

Though  the  coal  is  in  part  anthracite, !a  form  of  coal  popularly 
associated  only  with  the  true  Carboniferous  coal  regions  of 
Pennsylvania,  yet  by  the  fossils  associated  with  it  we  recognize 
it  as  the  same  so-called  “ lignite  ” coal  of  the  plains  and  foot-hills, 

* The  description  of  this  coal  field  is  drawn  from  my  report  of  1885,  with  some  cor 
rections  and  additions.  The  developments  in  the  field  have  not  materially  changed  any 
points  noted  in  that  report,  except  in  the  matter  of  output,  which  has  largely  increased. 


174 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


metamorphosed  or  changed  by  heat  into  anthracite.  It  is  in  the 
same  geological  horizon,  the  Upper  Cretaceous,  and  both  on  the 
roof  of  the  Anthracite  mine  and  the  coking  coal  mine  of  Crested 
Butte  we  find  the  same  familiar  Upper  Cretaceous  palm  and  plant 
leaves,  while  in  the  sandstone  at  the  base  are  the  seaweeds  (Haly- 
menites)  of  the  “ fucoidal  sandstone,”  and  below  that  again  in 
shales,  burnt  into  hard  black  slates,  are  the  shells  (Inoceramus 
problematicus)  of  the  marine  Cretaceous.  The  change  is  not  in 
the  geological  relations  of  the  coal,  but  in  the  physical  character 
of  the  coal  itself. 

That  the  coal  should  be  in  the  same  geological  horizon  as 
that  on  the  Eastern  plains  is  not  surprising,  if  we  consider  that 
the  front  range  and  the  Sawatch  were  at  one  time  parallel  reefs 
in  an  almost  universal  ocean.  The  same  sea  beat  against  the 
Eastern  and  Western  border,  depositing  marine  strata  of  a simi- 
lar nature  on  both  sides.  The  ranges  were  elevated  gradually, 
admitting  of  a land  and  fresh  water  area  on  both  slopes,  favorable 
to  the  growth  of  coal  vegetation.  The  energies  which  gave 
greater  elevation  to  these  ranges  found  relief  on  the  western 
flank  of  the  Sawatch,  in  violent  outbursts  of  molten  matter, 
which  welling  up  from  regions  below,  tossed  the  overlying 
sedimentary  beds  like  waves  in  a storm,  penetrating  them  by 
long  fissures  and  giving  birth  to  huge  bodies  of  lava  united 
to  one  another  by  dykes ; from  these  also,  between  the  strata, 
wedge-like  sheets  of  lava  were  intruded.  The  heat  thus  engen- 
dered and  continuing  long  after  all  active  eruption  had  ceased, 
permeated  the  surrounding  strata,  producing  more  or  less  gen- 
eral metamorphism  according  to  the  nearness  or  distance  from 
the  volcanic  source ; shales  and  clays  were  hardened  or  changed 
into  slate,  sandstone  into  quartzite,  limestone  into  white  marble ; 
brown  lignite,  into  semi-bituminous,  semi-bituminous  into 
bituminous,  that  into  coking  coal,  and  that  into  semi-anthra- 
cite and  anthracite,  and  we  may  yet  find  in  the  region  the  last 
degree  of  metamorphism  of  coal,  namely  graphite  or  black  lead. 
The  remaining  features  are  the  result  of  erosion.  After  the  gen- 
eral uplift  and  volcanic  disturbance,  which  was  at  least  after  the 
Cretaceous,  the  region  seems  still  to  have  been  a point  of  volcanic 
unquietness,  for  we  find  newer  dykes  penetrating  the  older  masses 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


175 


of  lava,  and  even,  I am  told  by  Mr.  Whitman  Cross,  of  the  United 
States  Geological  Survey,  remarkably  recent  looking  basalt  over- 
flows the  glacial  drift,  which  brings  the  date  of  volcanic  eruptions, 
as  at  Glenwood,  perhaps  up  to  the  human  period.  Faults  are  also 
observable,  some  probably  contemporaneous  with  the  erup- 
tions, but  others  trvaersing  eruptive  sheets  and  sedimentary 
strata  alike,  so  that  after  the  eruptive  forces  subsided,  regional  con- 
traction of  the  strata  disturbed  and  faulted  them  as  at  Leadville. 

In  a region  so  disturbed  and  so  influenced  by  heat  we  should 
expect  precious  mineral  veins,  and  such  we  find,  usually  as  fis- 
sure veins  at  contact  between  volcanic  and  sedimentary  rocks,  or 
in  one  or  the  other  formation  only.  The  gangue,  usually  quartz 
or  a “breccia”  of  quartz  and  slate,  carries  a variety  of  minerals, 
principally  iron,  copper  and  arsenical  pyrites  with  much  brittle 
and  native  silver,  in  wire  like  bunches,  in  pockets,  or  in  surface 
float,  also  ruby  silver.  Galena  is  less  common  than  usual  and  is 
generally  fine  grained  and  rich  in  silver. 

Gray  copper  also  occurs,  running  100  to  200  ounces  in  sil- 
ver. 

The  coke  and  coal  are  at  hand  ready  to  smelt  these  ores  and 
save  cost  of  shipping. 

Descending  the  Sawatch  range  by  the  Marshall  Pass  we  find 
ourselves  in  a plateau  region  extending  far  to  the  southwest  and 
west,  where  the  distance  is  closed  by  the  volcanic  San  Juan 
Mountains  ; the  intervening  country  is  covered  with  lava,  resting 
either  directly  on  granite  or  capping  horizontal  Cretaceous  beds. 
The  great  local  development  of  the  Cretaceous  accounts  for  the 
presence  of  the  large  coal  fields  of  the  region.  To  the  northeast 
appear  the  cones,  pyramids  and  castles  of  the  Elk  Mountains. 
Through  this  country  flows  the  Gunnison  River,  heading  by 
many  small  tributaries  in  the  Elk  Mountains  and  flowing  South 
in  a wide,  clear  stream,  emptying  into  the  Grand  River.  On  a 
broad  flat  on  its  south  bank  lies  Gunnison  City.  On  the  opposite 
bank  are  some  picturesque  cliffs  of  volcanic  breccia  upwards  of 
1,000  feet  thick  resting  upon  conglomerates  and  sandstones  of 
Cretaceous  age,  as  indicated  by  fossil  plants.  This  “breccia” 
covers  the  surface  and  fills  up  ancient  ravines  cut  in  the  sandstone, 
showing  that  the  surface  of  the  country  had  been  eroded  into  hill 


176 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


and  valley  before  the  volcanic  flood  of  lava  deluged  it,  over- 
whelming the  hills,  filling  up  the  ravines  and  reducing  the  surface 
to  a level,  now  cut  up  by  erosion  into  table  lands  or  “ mesas.  ” 
The  materials  composing  this  “ breccia  ” are  angular  blocks  of 
grey  lava  from  the  size  of  an  egg  to  a ton  in  weight,  cemented 
together  by  a paste  of  volcanic  sand.  A stratified  structure  is 
visible  as  if  the  “ejecta  ” had  been  deposited  under  the  influence 
of  water ; the  dip  is  about  20°.  The  “ breccia”  is  weathered  into 
phantastic  forms,  “hoodoos,”  pinnacles,  columns  often  with  a large 
block  of  lava  capping  a monument.  This  “ breccia  ” together 
with  some  beds  of  sandstone  form  the  banks  as  we  ascend  the 
river  for  some  miles,  then  granite  appears  in  the  canon  of  an  off- 
shoot of  the  Sawatch.  Upon  this,  Cretaceous  sandstone  rests 
directly  and  horizontally,  a geological  feature  different  from  that 
on  the  plains,  where  the  lower  rocks,  such  as  the  Trias,  Carbonif- 
erous or  Silurian  usually  occupy  that  position.*  In  places  the 
granite  is  either  bare  or  capped  with  “ breccia.  ” This  Cretaceous 
sandstone,  about  500  feet  feet  thick,  is  our  first  introduction  to 
the  coal  measures. 

The  tributaries  of  the  Gunnison  come  in  as  we  ascend  the 
stream,  first  Ohio  Creek  from  the  North,  heading  up  near  the 
anthracite  basin  of  Irwin,  with  coal  beds  along  its  course.  East 
River  soon  joins  the  main  stream  with  Taylor  River,  and  lastly 
Slate  River  comes  into  East  River.  As  we  ascend  Slate  River 
the  first  grand  group  of  the  Elk  Mountains  comes  in  sight. 
Domes  or  pyramids  of  ashen-gray  or  whitish  lava  carved  into 
pinnacles  and  spires  by  melting  snows,  rise,  bare  and  bleached, 
above  a dark  skirting  of  pine  trees;  such  are  Crested  Butte  Moun- 
tain, 1 1,830  feet  above  the  sea,  and  Gothic  Mountain,  twin  moun- 
tains, though  some  miles  from  each  other.  Others  present  a more 
castellated  or  table  form,  such  as  Teocalli  Mountain  where  tiers 
of  horizontal  red  strata  seem  lifted  bodily  up  on  a volcanic  dome. 
Other  great  grey  massive  domes  of  lava  are  deeply  sculptured 
by  broad  amphitheaters  at  their  crests,  suggesting  craters,  but  in 
reality  the  seats  of  by-gone  glaciers;  such  are  Wheatstone  Moun- 


* The  inference  is,  that  this  portion  of  Colorado  was  above  the  sea  during  the  whole  of 
the  Paleozoic  and  Part  of  the  Mesozoic  eras,  and  was  not  submerged  until  the  Cretaceous 
epoch. 


GEOLOGY  OF  COLORADO  COAL  FIELDS 


177 


tain  and  others.  We  halt  at  the  thriving  little  town  of  Crested 
Butte  on  the  bank  of  Slate  River  and  about  one  mile  west  of  the 
peak  which  gives  it  its  name.  The  town  is  located  close  to  the 
coal  mines  and  coke  ovens  of  the  C.  C.  & I.  Co. 

The  illustration,  reduced  by  Prof.  P.  H.  van  Diest  from  a 
sketch  of  the  writer’s,  will  give  an  idea  of  the  scenery  looking  up 
the  river,  and  the  line  and  area  of  the  workable  coal. 

To  the  right  and  east  is  Crested  Butte  Mountain,  an  eruptive 
mass  of  quartz  prophyry,  with  horizontal  Cretaceous  shales  at 
its  base.  Beyond  it  is  the  road  going  over  to  East  River  and 
Gothic  Mountain,  the  latter  being  in  a direct  northeast  and 
southwest  line  with  Crested  Butte  Mountain,  and  connected  with 
it  by  either  a dyke  or  an  overflow.  Opposite  Gothic,  Copper 
Creek  runs  up  to  Whiterock  Mountain,  one  of  the  centers  of 
eruption.  Its  huge  dome  of  ashen  grey  eruptive  diorite  is  thrust 
up  through  the  sedimentary  strata.  Opposite  Whiterock  Moun- 
tain is  the  Sylvanite  Mountain  and  mine  particularly  rich  in  wire 
and  native  silver,  in  a fissure  vein.  There  is  a whole  group  of 
mines  here  located  on  fissure  veins  in  eruptive  rock,  having  a 
general  northwest  and  southeast  direction.  Continuing  up 
East  River  to  the  northeast  of  our  sketch  is  Baldy  Mountain,  a 
near  relation  of  Gothic  Mountain  and  Belleview,  leading  on  to 
the  Snow  Mass  group,  in  the  direction  of  Rock  Creek.  This  is 
another  eruptive  “ focus.”  Between  the  Whiterock  and  Snow 
Mass  as  centers  of  disturbance  the  strata  are  folded  back,  reversed 
and  faulted  along  a line  of  fracture.  Dykes  and  igneous  sheets 
occur,  and  a general  metamorphism  has  taken  place;  hence  we 
have  on  Rock  Creek  coal  changed  to  anthracite,  limestone  into 
some  of  the  finest  white  marble  we  have  ever  seen  in  America, 
and  said  to  exist  over  a considerable  area  and  thickness.  Anthra- 
cite and  natural  coke  also  occur  where  a dyke  of  lava  has 
intruded  into  the  coal  strata.  These  important  deposits  await  only 
a railway  to  make  them  accessible  to  market.  The  marble  is 
likely  to  be  of  particular  importance  in  the  west.  All  these  phe- 
nomena are  heat  products  incident  to  the  eruptive  forces,  and 
possibly  also  to  the  mechanical  heat  produced  by  the  friction  of 
violently  folded  rocks  in  the  course  of  mountain  making. 

At  the  top  of  the  picture,  northwest,  Augusta  Mountain, 


i7» 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


with  the  Augusta  mine  at  its  summit,  and  Cascade  Mountain 
stand  between  the  forks  of  Poverty  Gulch  and  Slate  River.  This 
is  another  mining  area.  Pittsburg  village  lies  at  the  foot.  From 
this  point,  looking  down  Slate  river,  the  coal  strata  are  seen 
forming  a narrow,  steep,  flat-topped  bench,  on  either  side  of  the 
river,  rising  toward  the  north,  and  dipping  to  the  southwest,  as 
we  go  down  stream,  until  at  Crested  Butte  the  coal  reaches  the 
level  of  the  river  and  again  ascends  gently  towards  the  south  in 
the  direction  of  Wheatstone.  About  half  way  on  the  west  side 
“O  Be  Joyful”  Creek  and  gulch  cut  through  it,  and  opposite, 
on  the  east  bank,  is  the  Anthracite  Mesa,  with  the  anthracite 
mine  of  the  Colorado  Fuel  Company,  1,000  feet  above  the  level 
of  the  river.  The  same  anthracite  ridge  is  traceable,  on  a 
descending  scale,  to  Crested  Butte  Mountain  on  the  east  side, 
while  on  the  west,  at  a higher  level,  it  flanks  Mount  Emmons, 
and  is  cut  at  Crested  Butte  City  by  Coal  Creek  on  the  west, 
which  leads  up  to  the  Irwin  anthracite  basin,  twenty  miles  distant, 
and  is  continued  from  Coal  Creek  to  Baxter  Creek  by  the  ridge 
of  the  Colorado  Coal  and  Iron  Company’s  coking  coal  mines, 
gradually  passing  out  along  the  base  of  Mount  Wheatstone, 
where  the  coal  is  poor  and  is  said  not  to  coke.  The  valley  of 
Slate  Creek  is  from  a mile  to  one  half  a mile  wide,  rising  toward 
the  north.  It  divides  the  coal  plateau  in  two,  and  the  stream 
flows  through  the  trough  of  a synclinal  fold. 

It  appears  then  that  the  coal  area  here  consists  of  a narrow 
strip  of  gently  dipping  strata  about  fifteen  miles  long  by  two 
miles  wide,  sawed  out  in  the  center  by  Slate  River  Valley 
half  a mile  or  more  wide,  walled  in  by  volcanic  dykes  and 
eruptive  mountains  on  both  sides,  east  and  west  and  to  the 
north,  tipped  up  by  these  on  each  side  as  it  approaches  them. 
On  the  east,  Crested  Butte  and  Gothic  Mountain,  with  their 
dykes  limit  it.  Mount  Wheatstone  and  a twin  volcanic  moun- 
tain connected  probably  by  dykes  with  Mount  Emmons  limit  it 
on  the  west.  The  elevating  forces  seem  to  have  been  greatest 
towards  the  northwest,  where  prodigious  and  numberless  dykes 
give  evidence  of  great  volcanic  energy.  Thus  the  strip  of  coal 
strata  was  encircled  by  mountains  of  heated  lava  as  by  the  hot 
walls  of  an  oven,  metamorphosing  it  in  a gradual  gradation,  from 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


179 


bituminous  and  coking  coal  to  semi-anthracite,  and  finally  to 
anthracite ; the  metamorphism  increasing  as  we  go  up  the  gulch 
to  the  center  of  elevation,  volcanic  disturbance  and  heat.  The 
coal  field  is  a small  one,  for  when  not  restricted  merely  by  eros- 
ion (as  in  the  case  of  the  anthracite  mesa)  it  will  be  limited  when 
the  abutting  strata  cease  against  the  volcanic  walls.  It  is  a frag- 
ment of  the  greater  coal  field  of  the  country,  isolated  by  up- 
thrusts of  volcanic  lava  from  other  portions  of  the  basin,  such  as 
the  anthracite  basins  at  Irwin  and  Rock  Creek,  whose  geological 
position  is  the  same,  viz  : Upper  Cretaceous. 

With  regard  to  these  great  volcanic  masses,  some  are 
undoubtedly  huge  dykes  coming  up  from  below  and  eroded  into 
individual  peaks.  These  would  cut  off  the  coal  as  by  a wall. 
Others  again  are  intrusive  sheets  of  lava  issuing  from  a parent 
dyke  and  wedged  in  between  the  strata.  Others  may  be  “lacco- 
lites”  or  bodies  of  lava  coming  up  from  below,  but  which  not 
having  had  force  enough  to  reach  the  surface,  arched  up  the  over- 
lying  strata,  forming  a great  oven  shaped  cavity  filled  with  solid 
lava.  Remove  the  surface  rocks  from  this  by  erosion,  and 
dome-like  mountain  masses  of  lava,  such  as  Gothic  or  Crested 
Butte  would  result.  Wheatstone  and  similar  peaks  may  have 
the  same  origin,  they  have  not  much  disturbed  the  strata,  but 
have  gently  elevated  and  altered  it  by  their  heat. 

The  short  distances  within  which  the  changes  in  the  char- 
acter of  the  coal  occur  are  worthy  of  notice. 

At  the  base  of  Wheatstone  Mountain  the  coal  is  said  to  be 
bituminous,  and  not  coking.  Two  miles  up  stream,  at  the  Colo- 
rado Coal  and  Iron  Company’s  mines,  it  is  coking  and  charged 
with  inflammable  gases ; one  mile  further  north  it  becomes  semi- 
anthracite at  the  Warner  mine ; two  miles  further  it  is  genuine 
anthracite  at  the  Anthracite  Mesa,  and  continues  anthracite  to  the 
head  of  the  creek.  Within  a distance  of  six  miles  all  these 
changes  take  place.  It  will  appear  then  that  limited  as  is  the 
coal  field,  the  different  kinds  of  coal  are  still  more  restricted, 
coking  coal  will  be  limited  on  the  west  by  the  volcanic  wall 
stretching  from  Wheatstone  to  Coal  Creek,  and  about  three  to 
five  miles  back  of  the  Colorado  Coal  and  Iron  Company’s  coal 
hill  it  will  probably  become  more  anthracitic  and  less  coking,  as 


So 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


it  approaches  these  volcanic  limits.  There  is  area,  however,  enough 
for  many  years  to  come.  Less  than  a mile  north  of  it  the 
semi-anthracite  area  comes  in,  followed  by  the  true  anthracite, 
limited  in  the  same  way  by  the  Gothic  and  Crested  Butte  dyke 
on  the  east,  as  well  as  by  the  erosion  of  Washington  Gulch;  by 
a faulted  area  on  the  north,  and  on  the  west  side  by  the  dykes 
of  Mount  Emmons  and  “ O Be  Joyful  ” Creek,  and  to  the  north 
by  the  dykes  of  Augusta  Mountain  and  Poverty  Gulch. 

I have  traced  the  anthracite  coal  to  the  head  of  Poverty 
Gulch.  It  is  there  upwards  of  .2,000  feet  above  the  valley,  and 
would  be  difficult  of  development.  A narrow  strip  of  different 
varieties  of  coal  extends  from  one  end  of  the  valley  to  the  other, 
interrupted  by  gulches,  dykes  and  faults  for  a distance  of  about 
fifteen  miles,  but  unitedly  not  averaging  more  than  one  mile  in 
width  and  two  and  one-half  or  three  miles  in  greatest  width. 

THE  COLORADO  COAL,  COKE  & IRON  CO.’S  MINE  AT  CRESTED 
BUTTE. 

The  “ mesa”  or  hill  in  which  this  mine  lies,  is  about  two 
miles  long  by  three  miles  wide,  from  Baxter  Creek  on  the  south 
to  Coal  Creek  north,  limited  on  the  west  by  the  Volcanic  Moun- 
tains, and  east  by  the  Slate  River  Valley.  This  probably  repre- 
sents the  utmost  limits  of  the  coking  coal  area.  At  Crested 
Butte  the  coal  touches  water  level,  the  old  workings  being  below 
water  level  ; thence  it  seems  to  rise  gently  towards  Mt.  Wheat- 
stone. The  hill  is  ot  sandstones  and  shales  unaltered  by  heat, 
the  lower  portion  is  shale  ; the  hill  is  about  600  to  800  feet  high. 
On  Baxter  Creek,  in  a block  fallen  from  a bed  of  yellow  sandstone 
from  near  the  top  of  the  hill  and  in  close  proximity  to  the  coal,  I 
found  small  pectinated  shells  associated  with  stems  of  trees  that  may 
prove  of  interest  in  the  contest  of  geologists  as  to  whether  the  coal 
is  upper  Cretaceous  or  lower  Tertiary.  Above  this  sandstone  I found 
a coal  seam,  apparently  three  to  four  feet  thick,  and  another  about 
half  way  up  the  hill,  above  Baxter’s  house,  also  about  five  feet, 
(No.  1 of  analyses)  and  not  coking.  Miners  claim  there  are  five 
seams  in  the  hill,  beginning  from  the  base  with  intervals  of  shale 
and  sandstone. 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  i8r 


1 Seam io  feet,  not  cokable. 

2 „ ^ 4,  l cokable. 

3 5 J 

4 “ ....  4 “ not  cokable. 

5 2 “ 

27  feet. 


The  non-cokable  seams  might  prove  coking  if  worked  below 
water  level.  The  coal  seam  six  feet  thick  is  worked  close  to 
town ; the  new  opening  is  on  a bench  100  feet  above  the  river 
level.  The  old  workings  and  the  most  extensive  were  sunk  by 
drift  and  tunnel  below  the  water  level,  but  since  the  fire-damp 
accident,  owing  to  the  prevalence  of  faults  and  other  reasons, 
they  have  been  abandoned  and  are  now  full  of  water.  The  gen- 
eral dip  of  the  coal  is  to  the  west,  rising,  however,  as  it 
approaches  the  mountains.  The  new  entrance  tunnel  is  twenty 
feet  wide  by  six  feet  high  for  some  distance,  contracting  to  ten 
feet  within  the  main  entry.  Side  entries  diverge  from  this  at  an 
angle  of  45 0 and  are  run  diagonally  across  the  dip,  which  reduces 
its  steepness  from  8°  to  40  or  50,  quite  sufficient  for  the  down 
grade  of  the  laden  cars  to  the  main  entry.*  The  latter  is  also  so 
•driven  along  the  seam  and  dip  and  to  the  raise  as  to  afford  a gen- 
tle down  grade  of  two  feet  in  100  to  haul  the  laden  cars  to  the 
pit’s  mouth,  whence  they  run  down  an  incline  plane  on  rollers 
and  wire  ropes  worked  by  steam  to  the  shutes  and  are  discharged 
into  the  cars  close  to  the  coke  ovens. 

The  coal  seam  is  free  from  slate,  is  soft  and  easily  mined  with 
pick  alone,  no  powder  being  used  in  the  mine  since  the  fire-damp 
accident.  Two  men  can  turn  out  about  nine  tons  daily.  The 
roof  is  poor,  being  composed  of  shale  about  two  feet  thick,  over- 
laid by  treacherous  sandstone.  Masses  of  this  shale  slack  off  and 
fall  from  time  to  time,  involving  the  necessity  of  timbering. 
Accidents  in  mines  from  bad  roofs  are  the  commonest  in  Colo- 
rado, as  testified  by  the  inspector’s  report.  A ticking  sound  is 
heard  constantly  from  the  escape  of  gases  in  the  coal.  The  ven- 
tilation at  present  seems  ample.  A ventilating  furnace  is  built 


* The  greatest  distance  from  the  entrance  is  now  8,000  feet  Eleven  miles  of  track  are 
laid  in  this  mine. 


1 82 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


near  one  of  the  entries  and  an  eight  feet  Murphy  fan  is  erected 
sending  in  50,000  cubic  feet  of  air  per  minute. 

Ventilation  is  a most  necessary  feature  of  this  mine,  where 
gases  are  being  given  off  so  abundantly,  to  prevent  the  recur- 
rence of  the  terrible  accident  which  occurred  in  the  old  and  now 
abandoned  workings.  The  great  prevalence  and  accumulation  of 
gases  there,  may  have  been  due  largely  to  the  mine  being  driven 
below  water  level,  the  gases  being  thus  more  confined.  The 
present  workings  being  above  water  level  and  dry  and  nearer  the 
surface,  it  is  supposed  the  gases  find  some  exit  through  the 
surface  shales.  The  coal  being  naturally  full  of  gases,  these  will 
probably  increase  and  accumulate  with  greater  depth,  and  will 
need  an  abundant  supply  of  fresh  air  to  dilute  and  dissipate  them 
as  they  are  given  off.  As  gases  are  given  off  from  the  “ face  ” of 
the  coal,  the  more  the  area  exposed,  the  greater  will  be  the  accu- 
mulation of  gas.  “ Blowers,”  or  sudden  tbursts  of  gas  may  be 
tapped  at  any  time,  and  abundant  ventilation  is  necessary  to  dissi- 
pate them.  Care  is  also  necessary  to  prevent  their  taking  fire,  by 
the  use  of  safety  lamps,  and  the  absence  of  all  gunpowder  or 
explosive  material  commonly  used  in  development.  Such  pre- 
cautions are  being  taken  to  prevent  the  repitition  of  that  terrible 
catastrophe  which  is  too  fresh  in  people’s  minds  to  need  recount- 
ing here,  and  a full  account  of  which  will  be  found  in  Inspector 
Mc’Neil’s  report. 

The  origin  of  these  dangerous  gases  is  partly  a chemical  and 
partly  a geological  matter.  Carburetted  hydrogen,  or  fire  damp, 
C H4  and  carbon  dioxide,  or  choke  damp,  are  common,  princi- 
pally in  old  mines  that  have  attained  considerable  depth.  Heat 
is  the  prime  agent  in  distilling  these  gases  from  the  coal.  Such 
heat  may  be  derived  from  three  sources : first,  the  natural  heat 
of  the  earth  increases  an  average  of  one  degree  for  every  fifty  or 
sixty  feet ; secondly,  heat  is  produced  by  the  mechanical  folding 
and  crumbling  of  rocks  in  process  of  upheaval,  and  thirdly* 
hot  volcanic  rocks  are  usually  associated  with  such  plications- 
The  first  will  account  in  part  for  the  prevalence  of  these 
gases  in  the  deep  mines  of  the  old  world.  The  two  latter,  and 
especially  the  last,  will  account  for  the  presence  of  such  gases  in 
the  coking  coals  of  Crested  Butte.  “During  the  process  of  rock- 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


183 

folding  these  gases,”  says  Prof.  Geike,  “escape  and  the  proportion 
of  carbon  progressively  increases  in  the  residue  till  it  reaches  the 
most  highly  mineralized  anthracite,  or  may  even  pass  into  pure 
carbonor  graphite.  In  the  coalseams  of  Mons  and  Valenciennes  the 
same  seams  which  at  the  surface  are  in  a state  of  bituminous  coal 
gradually  loose  their  volatile  constituents  as  they  are  traced  down- 
ward till  they  pass  into  Anthracite.  In  the  Pennsylvania  region 
the  coals  become  more  anthracitic  as  they  are  followed  on  to  the 
Eastern  region,  where  the  rocks  have  undergone  greater  folding 
and  were  exposed  to  an  elevation  of  temperature.”  We  see  here 
then  a connection  made  between  the  process  of  gradual  change 
from  a bituminous  to  a coking  coal,  and  from  that  to  anthracite 
and  the  evolution  of  gases  due  to  the  heat  evolved  in  the  violent 
folding  to  which  this  region  has  been  subjected,  and  to  the  heat 
engendered  by  volcanic  eruptions. 

The  coking  coal  of  Crested  Butte  has  been  subjected  to  a 
moderate  heat  from  the  proximity  of  the  volcanic  mountains  back 
of  it,  and  also  from  a certain  amount  of  plication.  Lava  below 
the  surface  retains  a latent  heat  for  an  enormous  time  after  all 
eruption  has  ceased  This  heat  from  a distance  has,  we  think, 
slowly  and  partially  changed  the  coal,  and  in  doing  so  has  evolved 
gases  still  retained  in  the  strata  or  stored  away  and  accumulated 
in  cavities,  pockets  and  crevices,  such  as  the  crevices  on  the  line 
of  a fault  or  between  the  roof  and  the  coal.  The  old  workings 
encountered  such  faults  and  crevices  with  depth  and  hence  the 
“blowers.”  Gas  in  the  old  mine  came  principally  from  the  roof. 
On  the  other  hand,  the  anthracite  mine  has  no  gas,  because  it  has 
been  subjected  to  greater  heat  and  the  gases  thoroughly  driven 
off,  have  escaped.  “The  proportion  of  carbon  has  progressively 
increased  on  the  residue”  till  it  has  become  anthracite.  In  other 
words  the  coking  coal  is  half  cooked  and  retains  its  gases ; the 
anthracite  is  thoroughly  “done”  and  its  gases  driven  off. 

Doubtless  the  coal  of  this  mine  contains  the  greatest  amount 
of  dangerous  gas  in  the  State.  The  other  mines  of  Colorado 
are  generally  free  from  it,  especially  those  on  the  plain  aud 
border.  Probably  this  is  owing  to  less  folding  of  rocks  and  less 
manifestations  of  volcanic  agencies  there,  and  to  the  general 
character  of  the  coal  being  more  lignitic  or  bituminous  and 


184 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


unmetamorphic,  and  not  evolving  gases,  and  also  not  generally 
coking.  The  other  coking  area  at  Trinidad  probably  derives  its 
coking  qualities  from  the  same  source  as  at  Crested  Butte,  viz : 
the  proximity  of  eruptive  rocks.  The  coal,  however,  does  not 
give  off  anything  like  the  same  amount  of  gas,  if  any  at  all ; and  if 
it  did,  it  would  be  at  once  diluted  and  expelled  by  the  excellent 
natural  ventilation  of  those  mines.  The  New  Line  mine  at  Crested 
Butte  is  worked  on  the  pillar  and  stall  system.  The  main  entry 
is  cut  somewhat  diagonally  to  the  face  of  the  coal ; the  side  entries 
work  directly  on  the  “ face.”  The  only  disturbances  so  far 
encountered  on  the  strata  are  a few  “ rolls,”  one  of  which  crushes 
the  coal  down  from  six  to  two  feet. 

The  coal  of  this  mine  is  principally  devoted  to  coke  making, 
for  which  there  are  125  beehive  ovens,  s milar  to  those  at  El 
Moro,  close  to  the  mine.  The  coke  produced  is  probably  the 
best  in  the  State,  if  not  in  the  West,  being  compact,  firm,  not 
cellular,  free  from  slate,  with  little  sulphur  and  a moderate  per 
cent,  of  ash.  See  analysis  of  these  coals  and  cokes  by  Mr. 
Charles  A.  Gehrmann,  of  the  School  of  Mines,  at  the  close  of  this 
article.  It  is  claimed  for  it  “ that  there  is  less  ash  in  it  than  any 
other  American  coke ; that  it  equals  the  English  coke,  and  gives 
general  satisfaction  to  all  the  smelters  using  it.” 

This  mine  produced  in  1888,  155,966  tons  of  coal  and 
40,889  tons  of  coke. 

The  principal  markets  are  Utah,  Nevada,  Idaho,  Montana 
and  other  points  west. 

THE  SEMI-ANTHRACITE  AND  ANTHRACITE  MINES. 

Passing  up  the  valley,  about  a mile  above  the  Crested  Butte 
mine,  on  the  west  bank  of  the  river  are  the  openings  of  the 
Warner  & Durango  Trust  Co.  The  coal  is  semi-anthracite.  The 
seam  is  four  feet  thick,  and  the  mine  was  shut  down  at  the  time  of 
our  visit.  A few  feet  below  the  coal  are  fossil  and  sea  weeds,  “Haly- 
menites,”  in  the  “fucoidal  yellow  sandstone,”  and  the  same  is  trace- 
able on  the  opposite  river  bank  below  the  Anthracite  Mesa,  which 
shows  these  coal  seams  to  be  the  same  as  the  lower  seam  worked 
at  Trinidad  and  on  the  plains.  But  one  seam,  I think,  is  worked 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS.  185 

in  this  valley.  It  diminshes  in  thickness  as  we  ascend  the  valley, 
and  becomes  more  anthracitic.  From  this  to  the  head  of  the 
valley  the  marine  Cretaceous  shales  underlying  the  coal  are  ex 
posed,  changed  by  heat  into  slates,  but  bearing  unmistakable 
impressions  of  Inoceramus  shells,  characteristic  of  Cretaceous 
No.  4.  Up  “ O Be  Joyful  ” Gulch  Mr.  Holmes  found  in  1874,  a 
bed  of  semi-anthracite  two  feet  thick,  between  beds  of  quartzitic 
sandstones  and  metamorphosed  shales,  and  1 500  feet  above  the 
level  of  Slate  River.  Its  analysis  is  given  as  : 


Water 4 

Volatile  matter 14 

Carbon 74 

Ash  of  a reddish  color 8 


100 

From  this  we  cross  the  river  to  the  east  bank  and  ascend  the 
steep  slope  of  the  Anthracite  Mesa,  which  is  1500  feet  above  the 
river.  The  coal  area,  which  is  in  the  upper  500  feet,  occupies 
about  one  square  mile.  The  hill  is  composed  for  1000  feet  of  meta- 
morphosed shales,  capped  with  a sandstode  belt,  upon  which  rests 
the  coal  seam.  Above  this  are  500  feet  of  coal  strata  of  slates 
and  sandstones  and  coal  seams.  There  is  no  lava  cap  or  dyke 
immediately  associated  with  this  hill,  though  it  may  once  have 
existed  and  been  eroded  off,  as  it  is  visible  on  the  corresponding  side 
of  the  valley.  The  metamorphic  heat  may  have  been  derived  from 
the  proximity  of  Gothic  Mountain  and  its  dykes  a few  miles  east 
of  it.  Slate  river  runs  northwest  and  southeast,  and  the  coal 
dips  southwest  toward  the  canon  50  or  6°,  allowing  a fair  down 
grade  for  the  loaded  cars  to  the  entrance.  On  the  east  side  of 
the  mesa,  where  the  coal  is  cut  off  by  Washington  Gulch,  it  is 
said  to  dip  to  the  southwest  160.  Possibly  Gothic  and  Crested 
Butte  are  responsible  for  this  elevation.  The  mine  is  opened  by 
double  entry  on  the  face  of  the  mountain,  800  feet  above  the  coal- 
breaker  and  1000  feet  above  the  river.  The  coal  is  run  out  of 
the  mine  on  a down  grade  of  50  and  thence  discharged  on  a 
double  tramway  1600  feet  long  on  a grade  of  30°.  The  output 
is  250  tons  daily,*  and  the  coal  comes  out  in  large  solid  masses 

* The  production  for  1888  was  36,000  tons  of  anthracite. 


i86 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


and  is  transferred  to  the  coal  breaker  at  the  bottom  of  the  tram- 
way, where  it  is  broken  up  in  a crusher,  something  like  a quartz 
crusher,  from  which  it  passes  into  revolving  screens  with  meshes 
producing  five  different  sizes. 

No.  i,  about  the  size  of  a man’s  fist. 

No.  2,  Orange  size. 

No.  3,  Walnut. 

No.- 4,  Pea  coal. 

No.  5,  Culm  or  waste  left  on  the  dump,  but  not  breeding 
spontaneous  fires  as  is  common  with  the  “ slack  ” of  bituminous 
coal. 

A branch  of  the  Rio  Grande  Railroad  runs  up  Slate  Valley  to 
the  Breaker.  One  hundred  men  are  employed.  The  company  is 
“The  Colorado  Fuel  Co.”  The  shales  of  clay  forming  the  roof 
of  the  mine  are  baked  to  such  a degree  of  hardness  that  they 
form  an  excellent  roof  and  no  timbering  is  required.  The  floor 
is  equally  good.  The  seam  is  over  four  feet  thick.  There  are 
four  east  and  three  west  double  entries,  with  rooms  averaging 
6oo  feet.  The  rooms  run  in  ioo  yards  from  each  entry,  are 
twenty  feet  wide  with  pillars  of  coal  between  them  20x30  feet. 
The  air  of  the  part  of  the  mine  I visited  was  good,  no  noxious 
gases  are  given  off  by  the  coal.  Ventilation  is  by  furnace  in  one 
of  the  entries,  carrying  30,000  cubic  feet  of  air  per  minute,  com- 
municating with  the  surface  by  a twelve-foot  shaft  and  iron  smoke 
stack.  There  are  said  to  be  four  seams  also  in  this  hill,  the  same 
as  at  Crested  Butte,  one  near  the  top  of  the  mountain,  one  sixty 
feet  above  the  worked  seam,  three  feet  thick,  and  one  a few  feet 
below  it.  All  of  them  are  anthracite.  The  seam  worked  is 
doubtless  the  same  as  that  at  Crested  Butte  The  coal  breaker, 
the  only  one  in  Colorado,  is  an  elaborate  affair,  after  the  fashion 
of  those  used  in  anthracite  mines  in  Pennsylvania. 

From  the  Anthracite  Mesa  we  can  trace  the  anthracite  seam 
across  the  canon,  rising  to  a greater  height  as  it  is  traced 
north  to  Poverty  Gulch.  The  opposite  side  of  the  valley  is  a 
lofty  mesa,  2500  to  3000  feet,  composed  of  a series  of  benches 
and  terraces  ; the  lower  portions  are  black  metamorphic  Creta- 
ceous slates  with  Inoceramus  shells,  the  terraces  above  this  are 
sandstone  and  intrusive  beds  of  quartz-porphyry  standing  out 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


187 


according  to  their  relative  hardness.  Dykes  also  appear  cutting 
through  the  strata  and  sending  out  intrusive  sheets  of  porphyry. 

The  anthracite  coal  must  be  looked  for  in  the  upper  por 
tion  of  the  mountain,  from  1 500  to  2000  feet  above  the  creek. 
The  dividing  line  between  the  coal  bearing  strata  and  the  marine 
slates  is  well  defined  by  a bench  of  sandstone  which  forms  the 
floor  of  a wide  ainpitheatre  at  the  head  of  Poverty  Gulch.  Here 
we  found  an  anthracite  seam,  probably  two  to  four  feet  thick, 
overlaid  by  twenty  feet  of  sandstone,  resting  on  which  was  a bed 
of  porphyry,  doubtless  the  immediate  source  of  heat-producing 
anthracitism.  The  coal  runs  high  in  fixed  carbon.  (See  Analysis 
No.  7.) 

Cascade  Mountain,  between  Poverty  Gulch  and  Augusta 
Mountain,  is  a fragment  of  coal  and  Cretacious  strata,  faulted  off 
from  the  main  ridge.  The  mountain  is  a net-work  of  dykes  and 
intrusive  sheets  of  porphyry,  apparently  crossing  one  another. 
The  sandstones  are  changed  to  quartzite,  the  shales  to  slate  ; and 
the  whole  mass  seems  to  have  been  subsequently  shattered  by 
minor  faults.  Mineral  veins  occur  in  it. 

Similarly  the  walls  surrounding  the  ampitheatre  above  the 
anthracite  seam  are  riddled  with  dykes.  The  horizontal  coal 
strata  are  in  places  caught  up  in  the  fiery  embraces  of  a huge 
dyke  and  peep  out  from  the  blacker  slates. 

A wide  ampitheatre  is  also  at  the  head  of  Augusta  Moun- 
tain, from  which  descends  a series  ol  deep  benches  like  steep 
stairs  into  the  valley.  The  Augusta  silver  mine  is  at  the  top  and 
a tramway  on  the  endless  rope  and  bucket  system,  1^4  miles  in 
entire  length,  brings  down  the  ore  from  the  mine.  The  ore  of 
this  and  others  near  by  is  varied,  producing  fine  grained  galena, 
ruby  silver,  copper  and  iron  pyrites,  native  and  brittle  silver,  sul- 
phurets  and  gray  copper.  The  principal  mines  of  Poverty  Gulch 
are  the  Augusta,  Jacob  Strader,  Gift,  Big  Strike  and  Domingo.  I 
am  indebted  to  Mr.  Robinson,  of  Pittsburg,  for  his  guidance  over 
the  mountain. 


BOG  IRON  ORE. 

About  three  miles  up  Coal  creek,  on  the  road  from  Crested 
Butte  to  Irwin,  is  a deposit  of  bog  iron  ore.  It  occurs  by  the 


GEOLOGY  OF  COLORADO  COAL  LIELDS. 


side  of  the  road  in  a marsh  thickly  covered  with  moss  and  fallen 
timber  Where  trees  have  been  torn  up  by  the  roots  or  shallow 
prospect  holes  are  dug,  the  soil  is  impregnated  with  iron  oxide, 
and  the  pools  and  streamlets  are  red  with  the  same  mineral.  The 
oxide  solidifying  in  spongy  masses,  encloses  the  rootlets  of  trees 
and  moss  There  is  a low  bluff  on  the  marsh  of  the  same  char- 
acter. Both  marsh  and  bluff  are  thickly  strewn  with  boulders  of 
porphyry  drift.  The  iron  is  brought  down  by  water  passing 
through  a large  vein  of  pyrites  higher  up  the  mountain  dissolv- 
ing the  pyrite  and  depositing  it  as  an  oxide  in  the  swamp.  I 
could  not  estimate  the  thickness  or  the  exact  area  of  the  deposit. 
Prospect  holes  three  or  four  feet  deep  had  not  reached  bottom. 
The  marsh  and  bluff  rise  about  fifty  feet  above  the  road.  Judg- 
ing from  rusty  streams  issuing  for  a distance  of  one-half  a mile, 
it  might  be  one-half  a mile  square.  A survey  I found  of  it, 
makes  it  4880  feet  long  by  2320  feet  wide. 

The  ore  is  used  by  the  Colorado  Coal  & Iron  Company,  for 
refining  gas  at  the  gas  works.  It  runs  over  fifty  per  cent,  in 
metallic  iron. 

IRWIN. 

From  thence  I rode  to  Irwin.  Here  are  painful  relics  of  the 
former  overrated  boom  which  has  abandoned  this  camp,  in  the 
form  of  capacious  and  silent  stamp  mills,  substantial  frame  houses 
and  stores,  deserted  or  fallen  in,  of  a once  booming  little  town 
now  but  a small  village.  I put  up  my  horse  in  the  deserted  store 
of  the  “ Reasonable*  (?)  Abe  ” and  fed  him  off  the  counter ! 

There  are  some  good  mines  and  prospects  here  worthy  of  a 
steady  camp.  Such  are  the  Forest  Queen,  Ruby  Chief,  Bullion 
King  and  others.  They  are  located  mostly  at  the  contact  be- 
tween porphyry  dyke  and  intrusive  beds,  and  Upper  Cretaceous 
sandstone.  The  veins  are  true  fissures.  Faults  have  occurred  in 
some,  leading  to  expensive  prospecting  for  the  true  vein.  The 
gangue  or  crevice  matter  is  a hard  quartz,  sometimes  brecciated 
with  slate  and  containing  numerous  geodes  and  pockets  of  quartz 
crystals.  The  vein  of  the  Forest  Queen  varies  in  width  from  five 

* This  “Reasonable”  gentleman  in  skipping  the  region  left  behind  him  a vast 
accumulation  of  debts. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


189 


to  twenty  feet ; is  nearly  vertical  and  at  contact  between  a por- 
phyry dyke  and  Cretaceous  sandstone.  The  ore  is  arsenical 
pyrites,  with  antimony  and  brittle  silver.  Reduction  works  are 
on  the  plant.  Some  rich  surface  “ sulphuret ore  occurs  as  an 
alteration  product  on  the  surface,  “ playing  out  ” as  it  passes  down 
into  unaltered  combinations.  An  anthracite  seam  of  excellent 
quality  and  fair  thickness  occurs  near  hear  on  Anthracite  creek.  t 
It  is  described  in  the  United  States  Survey  Report  of  1874: 

“ The  coal  is  exposed  on  both  sides  of  the  creek.  The  beds  are 
tipped  up  about  25 0 against  the  eruptive  range,  forming  the 
divide  between  Anthracite  and  Ohio  creeks.  The  coal  is  four  to 
five  feet  thick,  and  probably  the  same  as  at  Coal  creek.  An 
eruption  of  lava  occurs  100  feet  above  the  coal,  and  probably  so 
heated  as  to  deprive  it  of  bituminous  matter,  and  change  it  to 
anthracite.  An  analysis  gives  : 


Water ...  2.00 

Volatile  matter 2.50 

Fixed  Carbon 91.90 

Ash,  reddish 3.60” 


The  mine  is  not  working  at  present  owing  to  the  distance 
from  the  railroad. 

On  Rock  creek  the  coal  alluded  to  is  an  anthracite.  Above 
it  is  a mass  of  eruptive  rock.  The  coal  is  five  feet  thick.  Anal- 


ysis : 

Water  and  volatile  matter 7.40 

Fixed  Carbon 88.92 

Ash,  reddish 3.68 


100.00 

ANALYSES  OF  COALS  FROM  THE  CRESTED  BUTTE  REGIONS  BY  CHARLES 
A.  GEHRMANN,  OF  THE  SCHOOL  OF  MINES. 

Prof.  Arthur  Lakes , State  School  of  Mines : 

Dear  Sir  : I herewith  submit  the  results  of  analyses  of  coals 
submitted  to  me,  together  with  a few  remarks  as  to  their  com- 
parative value  so  far  as  determinable  by  chemical  examination. 

Yours  Respectfully, 

CHAS.  A.  GERHMANN. 
Golden,  Colo.,  January  1,  1886. 


190 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


The  coals  named  in  the  present  report  are  all  from  the  neigh- 
borhood of  Crested  Butte  and  include  both  the  coking  and  non- 
coking bituminous  coals  from  the  mines  of  the  Colorado  Coal  & 
Iron  Co.,  the  coke  made  from  the  former,  in  the  company’s 
ovens,  and  three  examples  of  anthracite  and  semi-anthracite. 
The  method  of  analysis  employed  was  that  which  is  ordinarily 
used  and  known  as  “proximate”  anlaysis.*  No  other  explanation 
is  deemed  necessary,  as  the  method  is  familiar  to  all  analytical 
chemists.  The  samples  compare  very  favorably  with  the  best 
Eastern  coals.  Especially  is  this  true  of  the  coking  coal,  which 
in  general  composition  is  equal  to  the  best  Eastern  gas  coals. 
The  coke  produced  from  this  coal,  as  seen  by  the  analysis,  con- 
tains somewhat  more  ash  than  would  be  calculated  from  the  anal- 
ysis of  the  coal.  Possibly  the  coal  sample  was  above  the  general 
average  of  the  mine,  but  the  coke  analysis  (No.  3)  is  better  than 
that  of  most  American  coke,  when  fairly  sampled,  as  this  was, 
from  large  lots.  The  sulphur  was  in  each  case  estimated  in  a 
separate  portion  and  is  of  course  included  in  the  summations  of 
the  “ proximate  ” analyses 

No.  1.  Surface  coal  of  upper  seam,  South  end  of  C.  C.  & I. 
coal  mountains,  near  Baxter  creek,  (non-coking): 


Moisture 

Volatile 

Fixed  carbon 

Ash 

6.53  per  cent. 

51.41 

39.81  “ 

2.25  “ 

Color  of  ash,  white. 

Sulphur,  0.437  per  cent. 

100.00 

No.  2 Coking  coal  of  C.  C.  & I. : 

Moisture 

Volatile  

Fixed  carbon 

Ash 

1. 1 7 per  cent. 
36.80  “ 

58.01 

4.02  “ 

Color  of  ash,  reddish  brown. 
Sulphur,  0.454  per  cent. 

* Hinrich  Geol.  Survey  of  Iowa  Chemical  Report* 

100.00 

GEOLOGY  OF  COLORADO  COAL  FIELDS . 


191 


No.  3.  A second  sample  of  the  C.  C.  & I.  coking  coal  from 
entry  No.  6 : 


Moisture  . . 
Volatile  . . 
Fixed  carbon 
Ash  ...  . 


1.94  per  cent. 
38.18  “ 

56.80  “ 

3.08  “ 


Color  of  ash,  salmon. 

Sulphur,  not  determined. 

No.  4.  Coke  (made  from  above  coal): 

Moisture 

Volatile 

Fixed  carbon 

Ash 


1 00.00 


0.05  per  cent. 
1. 15  “ 

89.12  “ 

9.68 


100.00 

Color  of  ash,  light  reddish  brown. 

Sulphur,  0.523  per  cent. 


No.  5.  Semi-anthracite,  from  near  Warren’s  coal  bank  : 


Moisture  . . 
Volatile 
Fixed  carbon 
Ash  .... 


0.64  per  cent. 
11.88  “ 

82.70  “ 

4.78  “ 


100.00 

Color  of  ash,  reddish  brown. 

Sulphur,  0.955  per  cent. 


No.  6.  Anthracite  coal,  from  anthracite  mesa  two  miles 
northwest  of  C.  C.  & I.,  on  east  bank  of  Slate  creek : 


Moisture  . 
Volatile  . . . 
Fixed  carbon 
Ash  .... 


0.72  per  cent. 

6.36 

86.92  “ 

6.00  “ 


10000 

Color  of  ash,  reddish  brown. 

Sulphur,  0.763  per  cent. 


IQ2 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


No  7.  Anthracite  seam,  in  Poverty  Gulch  (from  surface)  : 


Moisture 

Volatile 

Fixed  Carbon 

Ash 

. . 2.63 

88.32 

5-58  “ 

100.00 

Color  of  ash,  reddish  brown. 
Sulphur,  0 438  per  cent. 


COLORADO  ANTHRACITE. 

BY  PROF.  J.  S.  NEWBERRY. 

The  Anthracite  coal  mine  near  Crested  Butte,  has  now  been 
worked  for  several  years  by  the  Colorado  Fuel  Company,  has 
railroad  connections  with  the  Denver  market,  and  its  product  is 
there  a well  know  staple.  The  coal  seam  is  from  four  to  six  feet 
in  thickness  and  the  coal  is  a hard  bright  anthracite,  resembling 
in  appearance  and  not  inferior  in  quality  to  that  taken  from  the 
Pennsylvania  mines.  The  area  above  the  valley  of  Slate  river 
available  for  working  is  about  500  acres.  Perhaps  the  mountain 
opposite  the  Anthracite  mine  may  be  found  to  contain  more  than 
is  yet  known  to  exist,  but  without  further  discoveries,  it  would 
be  unsafe  to  estimate  the  coal  area  of  Slate  river  valley  at  more 
than  2000  acres. 

At  Irwin  14  miles  west,  there  is  an  area  of  anthracite  of 
1500  to  2000  acres.  The  coal  is  of  good  thickness  and  quality, 
as  silvery  and  brilliant  as  any  from  the  Lehigh  basin,  but  this 
field  has  as  yet  no  outlet  by  railroad.  The  anthracite  of  Gunni- 
son Mountain,  of  which  so  much  was  hoped,  has  proved  to  be 
very  limited  in  quantity,  and  is  for  the  present  quite  inaccessible ; 
that  of  Ragged  Mountain,  still  farther  north,  is  open  to  the  same 
objection,  and  though  of  good  quality,  is  shown  by  the  investi- 
gation of  Mr.  R.  C.  Hills  to  be  cut  off  at  no  great  distance  in  the 
rear  of  the  outcrop  by  the  eruptive  rocks  which  have  metamor- 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  193 

phosed  it,  and  the  quantity  is  therefore  small.  The  Muncie 
anthracite,  north  of  the  last  mentioned  locality,  has  been  pur- 
chased by  the  Midland  Railroad,  but  it  is  questionable  whether  it 
will  prove  sufficient  in  quantity  and  quality  to  warrant  the  large 
expenditure  necessary  to  open  a way  to  it. 

The  localities  enumerated  include  all  the  important  deposits 
of  anthracite  coal  yet  known  in  Colorado.  From  its  mode  of 
formation  the  area  of  anthracite  must  necessarily  be  small.  It  is 
confined  to  the  localities  where  the  eruptive  rocks  have  burst 
through  the  coal  series,  and  the  influence  they  have  exerted  has 
been  sufficient  to  produce  anthracite  only  for  a short  distance. 
Hence  we  may  conclude  that  the  anthracite  of  Western  Colo- 
rado, excellent  as  it  is  in  quality,  is  not  destined  to  be  an  import- 
ant factor  in  the  future  history  of  the  State. 


ANALYSES  OF  ANTHRACITE  BY  PROF.  J.  S.  NEWBERRY. 

Anthracite  of  the  Anthracite  Mesa,  Crested  Butte. 


Moisture 1.56 

Volatile  matter 5.93 

Fixed  Carbon 88.76 

Ash 3 75 

1 00.00 

Sulphur 048 

Phosphorous 0.067 


IRWIN  ANTHRACITE.  (iRWIN). 


Moisture • • 2.77 

Volatile  matter • 6.55 

Fixed  Carbon 84.81 

Ash 5.87 

100.00 

Sulphur • 0.79 

Phosphorous 0027 


i94 


GEOLOGY  OF  COL  OF  ADO  COAL  FIELDS. 


GUNNISON  UPPER  SEAM  OF  ANTHRACITE. 


Moisture 0.09 

Volatile 9.68 

Fixed  Carbon 81 .93 

Ash 8.30 

100.00 

Sulphur 0-547 

Phosphorous 0.039 


CHAPTER  X. 


Coals  of  Gunnison  Mountains. 


Chapter  X. 

COALS  OF  GUNNISON  MOUNTAINS. — BY  PROF.  J.  S.  NEWBERRY. 

West  of  Crested  Butte  the  Laramie  coal  series  is  pierced  by 
several  great  masses  of  volcanic  rock,  a rhyolite,  light  gray  in 
color,  with  numerous  large,  often  opalescent  cystals  of  Sanidin 
feldspar.  This  composes  Mt.  Beckwith,  Mt.  Marcellina,  the 
Ragged  Mountains,  Mt.  Gunnison,  etc.,  with  numerous  dykes  and 
intrusive  sheets  which  penetrate  the  sedimentary  strata  to  some 
distance  from  the  volcanic  vents.  From  these  mountains  one 
looks  out  westward  on  to  the  broad  plateaus  of  Grand  and  Bat- 
tlement Mesas,  an  unbroken  portion  of  the  sheet  of  coal-bearing 
rocks  which  occupies  all  the  interval  to  the  Wasatch.  Between 
the  eruptive  masses  the  strata  are  generally  much  warped  and 
broken,  but  along  the  North  Fork  of  the  Gunnison,  in  many 
places,  they  lie  nearly  horizontal,  the  coal-beds  being  above 
drainage  and  accessible.  On  the  east  side  of  Mt.  Gunnison  a 
plateau  of  this  character  forms  the  most  interesting  and  valuable 
tract  of  coal  land  I have  anywhere  seen.  Coal  creek  cuts  into 
this  plateau  to  the  depth  of  500  to  1000  feet,  exposing  at  the 
bottom  the  Colorado  Cretaceous  shales,  and  above  them  the  base 
of  the  Laramie,  soft,  yellow  sandstones  and  gray  argillaceous 
shales.  Near  the  top  of  the  cliffs  lies  an  intrusive  sheet  of  rhyo- 
lite, similar  in  general  appearance  and  relations  to  the  Palisades 
on  the  Hudson  river. 

In  this  section,  in  addition  to  smaller  beds,  are  four  finer  coal 
seams  than  I have  elsewhere  seen  in  one  exposure.  Of  these  the 
first  and  lowest  is  10,  the  second  13^,  the  third  10,  and  the 
fourth  10  feet  in  thickness.  The  uppermost  lies  within  a few  feet 
of  the  trap  sheet,  and  at  places  this  comes  down  immediately 
upon  it,  converting  it  into  anthracite.  The  third  seam  is  25  feet 
below  the  fourth,  and  they  are  much  alike  in  character.  The 
second  seam  from  the  bottom  is  1 3 to  15  feet  in  thickness,  having 
been  somewhat  eroded  by  the  current  which  spread  over  it  the 


:9B 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


material  of  the  sandstone  roof.  This  has  one  parting,  a band  of 
“ smut”  four  to  six  inches  in  thickness,  about  six  feet  above  the 
base;  a good  feature  on  the  seam,  as  it  will  permit  its  being 
worked  on  two  benches,  and  make  the  “ bearing  in  ” under  the 
upper  bench  easy.  With  the  exception  of  this  parting  the  coal 
is  very  homogeneous  and  pure.  Like  many  other  Laramie  coals 
this  contains  numerous  particles,  scales  or  lumps  of  a yellow 
resin  which  resembles  amber,  but  is  a secondary  product,  having 
been  distilled  from  the  ’ substance  of  the  coal  long  subsequent  to 
its  formation,  accumulating  in  its  joints  and  cavities. 

The  character  of  all  the  coal  seams  on  Coal  Creek  is  similar, 
though  the  upper  seams  are  somewhat  dryer  from  their  proximity 
to  eruptive  trap  rock.  All  are  hard,  bright,  and  homogeneous, 
working  large  and  coming  out  in  blocks  like  quarry  stone.  To 
the  experienced  coal-miner  nothing  could  be  more  attractive  than 
the  solid,  black,  shining  walls  they  present  when  opened. 

In  composition  these  coals  are  most  like  our  open-burning 
bituminous  coals  of  the  Alleghany  coal  fields,  but  contain  more 
gas,  and  show  little  tendency  to  coke.  They  contain  four  to  five 
per  cent,  of  water,  and  from  four  to  seven  per  cent,  of  ash ; the 
second  and  fourth  seams  one-half  per  cent,  of  sulphur ; the  third 
nearly  one  and  one-half  per  cent. ; in  phosphorous  they  are  all 
low.  The  lowest  seam  of  the  series  is  not  as  well  shown  as  the 
others  but  it  is  apparently  softer  and  will  probably  coke  better. 

The  coals  of  the  country  drained  by  the  North  Fork,  where 
not  locally  converted  into  anthracite,  are  exemplified  by  those 
just  described.  Some  of  them  will  coke,  but  they  must  be  gen- 
erally classed  as  open-burning.  Whether  they  can  be  used  in  the 
raw  state  for  smelting  remains  to  be  seen,  but  in  my  judgment 
with  proper  appliances  and  management  this  may  be  done.  As 
steam  coals  and  household  fuels  they  have  no  superior,  and  it  will 
not  be  many  years  before  they  will  be  taken  through  the 
mountains  by  railroads  in  large  quantities  to  supply  the  ever 
increasing  want  of  good  fuel  in  the  Prairie  States. 


GEOL  OGY  OF  COL  ORA  DO  COAL  FI  EL  DS. 


ANALYSES  OF  COALS  OF  THE  GUNNISON  MT.  DISTRICT, 
BY  PROF.  NEWBERRY. 

GUNNISON  UPPER  SEAM  IO  FEET  THICK. 


Moisture 3-803 

Volatile  Matter  40.155 

Fixed  Carbon 5 1 . 1 78 

Ash 4.341 

Sulphur 0.523 


100.000 

Phosphorus 0029 

GUNNISON  UPPER  SEAM,  ANTHRACITE. 

Moisture 0.910 

Volatile  Matter . 9.313 

Fixed  Carbon 80.932 

Ash 8.298 

Sulphur 0.547 


100.000 

Phosphorus 0.039 

GUNNISON  SECOND  SEAM,  IO  FEET  THICK. 

Moisture 4.93 

Volatile  Matter . ...  38.83 

Fixed  Carbon  47-91 

Ash  6.94 

Sulphur 1.39 


Phosphorus 


100.00 

0.054 


GUNNISON  THIRD  SEAM,  13^  FEET  THICK. 


Moisture  5.23 

Volatile  Matter 41.92 

Fixed  Carbon 48.43 

Ash 395 

Sulphur 0.47 


Phosphorus 


1 00.00 
0.080 


200 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


BALDWIN  MINES. 

On  Ohio  creek,  eighteen  miles  from  Gunnison,  along  the 
line  of  the  Denver,  South  Park  & Pacific  Railroad,  the  Baldwin 
Mines  have  been  for  some  years  operated  by  the  Union  Coal 
Company.  According  to  the  inspector’s  report  the  seam  is  4 feet 
6 inches  wide,  of  semi-bituminous  coal  dipping  40  and  developed 
by  a shaft  150  feet  deep.  At  106  feet  from  the  surface  a small 
seam  is  encountered  about  one  foot  thick,  followed  30  feet  below 
by  the  main  seam  somewhat  as  at  Golden  and  Louisville.  Below 
this  lies  a heavy  body  of  sandstone.  The  production  for  1888 
was  14,174  tons. 

Another  mine  on  the  same  creek  owned  by  the  Ohio  Creek 
Anthracite  Company,  lying  to  the  west  of  Mt.  Carbon  and 
twenty  miles  from  Gunnison  City,  finds  the  seam  4'  6"  of  bitu- 
minous coal  dipping  350  and  outcropping  in  the  mountain  side 
400  feet  above  its  base.  A cross  cut  turned  S'  6"  wide  by  7 
feet  high  is  driven  in  1150  feet  on  a gentle  grade  to  drain  the 
mine  and  intersect  the  coal  seam.  Where  it  intersects  the  latter 
levels  are  run  north  and  south  on  the  edge  of  the  seam.  The 
coal  left  above  will  be  stoped  out  by  rooms  and  pillars,  chutes 
being  let  down  to  hoppers  on  the  main  level  to  the  pit  cars. 
Twenty  coke  ovens  have  been  constructed  and  more  are  in  pro- 
cess of  erection.  A branch  line  from  the  Denver  and  South  Park 
road  is  expected  to  this  point. 

“The  coal  field  commences  south  of  Mt.  Carbon  in  a wedge- 
like shape,  widening  until  it  covers  a width  of  sixty  miles,  and 
extends  over  100  miles  in  length  in  the  direction  of  Grand  Junc- 
tion. Portions  of  this  field  are  also  found  near  Ouray  along  the 
skirts  of  the  San  Juan  Mountains.  The  coal  varies  in  quality, 
being  poor  where  the  covering  is  light  and  becoming  more  bitu- 
minous where  it  is  heavily  covered  and  even  anthracitic  as  it 
approaches  the  neighborhood  of  volcanic  action.  The  bitumi- 
nous coking  coal  is  generally  found  in  proximity  to  the  anthra- 
cite districts  and  the  lignitic  or  inferior  coals  cover  the  larger 
areas.” 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


201 


COALS  OF  THE  WHITE  RIVER  COUNTRY. 

“ These  are  simply  an  extension  northward  of  those  which 
crop  out  on  Grand  river,  and  they  have  been  opened  at  various 
intermediate  points.”  Large  bodies  of  such  coal  are  said  to 
exist  in  the  neighborhood  of  Meeker,  some  fifty  miles  north 
of  Newcastle,  but  according  to  Mr.  R.  C.  Hills  they  are  infe- 
rior in  quantity  and  quality  to  those  found  in  the  country 
between  Glenwood  Springs  and  Gunnison.  The  reason  for  their 
inferior  character  may  be  the  comparatively  undisturbed  nature 
of  the  strata  of  those  regions. 

Says  Prof.  Newberry  : “ In  going  down  the  Grand  river  from 

Pinon  Basin  the  Laramie  coal  series  is  found  continuously  to 
Grand  Junction  and  thence  westward  to  the  Wasatch.  Much  of 
this  country  I have  been  over  and  have  examined  the  coal  in  a 
great  number  of  localities,  and  while  the  seams  are  of  good 
thickness  and  fair  quality  in  many  places,  they  are  less  thick,  and 
the  coals  are  less  varied  and  pure  than  in  the  belt  of  country 
between  Glenwood  and  Gunnison.  At  Coalville,  Castle  Valley, 
Pleasant  Valley,  Cedar  City,  and  Kanawa,  are  seams  of  coal 
which  have  already  been  somewhat  worked  and  have  been  proved 
to  be  of  fair  and  sometimes  of  excellent  quality.  The  same  is 
true  of  the  country  bordering  on  the  Union  Pacific  Railroad, 
where  at  Evanston,  Rock  Springs,  etc.,  large  quantities  of  coal 
are  mined  which  is  much  esteemed  for  domestic  fuel  and  for  the 
generation  of  steam.  Yet  nowhere  in  all  this  region  is  the  coal 
equal  in  quality,  quantity  and  variety  to  that  found  in  the  country 
between  Grand  river  and  the  Gunnison.  Adding  to  this  belt  the 
coals  of  White  river  and  the  intervening  district,  we  have  some 
4,000  square  miles  of  coal  land  in  western  Colorado  which  will  bear 
comparison  with  any  equal  area  of  Carboniferous  coals  in  the 
valley  of  the  Mississippi.  The  importance  of  this  coal  field  to 
the  inhabitants  of  Colorado  and  the  adjacent  prairie  region  can- 
not be  overestimated;  and  however  productive  the  mines  of  gold 
and  silver  of  this  highly  favored  State  may  become,  I cannot  but 
think  that  her  coal  mines  will  prove  the  most  important  source  of 
her  wealth,” 


202 


GEOLOGY  OF  COLORADO  COAL  LI  ELDS. 


GENERAL  REVIEW  OF  THE  NORTHWESTERN  COAL  FIELDS  OF 
COLORADO,  BY  MR.  HEWITT. 

“ This  portion  of  the  State,  being  the  northern  half  of  its 
Pacific  slope,  is  drained  by  four  rivers,  the  Gunnison,  Grand, 
White  and  Yampa  or  Bear,  which,  with  the  Green,  flowing  south 
from  Wyoming,  unite  to  form  the  Colorado.  These  streams,  fed 
by  the  snows  of  the  Rocky  Mountains,  fall  from  an  altitude  of 

10.000  to  12,000  feet,  at  their  sources,  to  4,000  feet,  at  the  con- 
fluence of  the  Grand  and  Green  in  Utah,  near  the  State  line. 

This  area,  about  150  miles  square,  was  the  scene  of  great 
development  in  the  period  subsequent  to  the  Carboniferous;  but 
earlier  formations  have  meagre  representation.  The  whole  geo- 
logical section  is  torn  and  contorted  in  every  period  up  to  the 
most  recent,  by  the  movements  that  made  the  Continental  divide 
and  many  outlying  peaks  and  high  plateaus. 

A single  instance  may  serve  to  illustrate  the  extent  of  this 
action.  The  Silurian  limestones  are  lifted  and  partially  eroded 
to  form  a plateau  fifty  miles  across,  between  the  Grand  and 
White  rivers,  three  thousand  to  five  thousand  feet  above  their 
level  and  fifty  miles  west  of  the  range. 

The  direction  of  all  these  rivers  was  determined  by  anticlinal 
cracks  and  fissures,  since  eroded  with  canons  of  2,000  to  3,000 
feet  in  depth.  These  streams  and  their  tributaries  show  abun- 
dant evidence  of  glacial  action,  to  which  is  largely  due  the  extent 
of  the  arable  land  in  upper  benches  and  mesas.  Until  1882  nearly 
all  this  area  belonged  to  the  Ute  Indians. 

Where  the  Carboniferous  measures  are  exposed,  they  have 
been  crushed  and  twisted  between  the  heavy  limestones  and 
quartzites  below,  and  the  enormous  Jura-Trias  above;  and  though 
they  contain  coal,  it  is  extremely  unlikely  that  any  of  it  possesses 
commercial  value.  The  Jura-Trias  red  sandstones  are  3,000  to 

5.000  feet  thick,  and  their  fractures  have  canoned  all  the  streams 
of  the  Piedmont  region  at  least  once  in  their  course.  On  top  of 
these,  separated  by  the  Atlantosaurus  shales,  is  the  Dakota  sand- 
stone, a very  prominent  ledge,  50  to  100  feet  thick.  In  this  sand- 
stone is  the  horizon  of  a coal  seam  that  may  be  of  value  between 
the  White  and  Yampa  Rivers  and  elsewhere. 


GEOLOGY  OF  COL  OF  A BO  COAL  FIELDS. 


203 


Above  this  ledge  are  1,500  to  2,500  feet  of  Colorado  and 
Fox-hill  shales,  that  when  upturned,  are  easily  eroded,  and  have 
formed  a chain  of  parks  below  the  coal  measure  sandstones. 

The  productive  Cretaceous  coal  measures  are  700  to  1,200 
feet  thick  and  contain  two,  possibly  three  series  of  coal  seams. 

Above  the  coal,  the  softer  sandstones  and  shales  of  the  Post- 
Cretaceous,  about  1,000  feet  thick,  have  usually  been  eroded  to 
gentle  slopes. 

Over  the  larger  part  of  the  basin,  the  section  is  increased  by 
at  least  3,000  feet  of  Tertiary  measures,  containing  some  petro- 
leum shales  that,  when  fresh,  yield,  on  heating,  considerable 
vapor. 

Since  the  region  was  outlined  by  fractures  that  determined  the 
courses  of  the  rivers,  many  basaltic  overflows  have  occurred  ; 
and,  as  these  cap  all  the  geologically  aud  topographically  high 
ground,  it  is  probable  that  the  whole  basin  was  so  covered.  In 
the  bed  of  the  Eagle  river,  above  its  junction  with  the  Grand, 
near  Dotsero  station,  is  a lava  flow  so  recent  that  though  the  bed 
of  the  stream  was  changed  by  it,  the  edge  is  almost  intact,  and 
the  adjoining  partially  vitrified  shale  has  not  been  eroded. 

The  coal  measures  underly  most  of  this  regiondn  two  great 
fields  ; one  extending  from  the  north  side  of  the  drainage  basin  of 
the  Gunnison  to  the  southern  water-shed  of  the  Yampa,  with  the 
eastern  and  northern  outcrops  thrown  up  to  from  30  to  90°,  and 
the  southern  flat;  the  other  a part  of  the  Green  river,  (Wyoming,) 
field,  extending  into  this  State  about  40  miles  on  the  upper 
Yampa  river. 

As  far  as  observed,  these  coal  seams  where  unchanged  by 
flexure  with  consequent  heat  and  pressure,  carry  a lignite  con- 
taining from  five  to  twenty  per  cent,  of  water ; so  that  it  is  prob- 
able that  the  better  coal  will  be  found  only  on  the  narrow  east  and 
north  margin  where  the  pitch  averages  45 °.  In  the  southeast- 
ern corner  of  the  field,  on  the  head  waters  of  the  Gunnison,  the 
seams  are  horizontal,  but,  being  in  narrow  and  detached  patches 
have  been  locally  metamorphosed  so  that  in  four  miles  the  same 
seams  are  anthracite,  coking,  and  dry  coal. 

Going  north  from  this  point,  anthracite  is  found  in  patches 
high  on  the  sides  of  Mount  Marcellina  and  the  Ragged  Moun- 


204 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


tains.  The  last  peak  of  the  latter,  Chair  Mountain,  carries  on  its 
northern  slope  from  9,000  feet  altitude  to  10,000  feet,  a tongue  of 
outcrop  that  is  proved  to  be  anthracite.  Two  seams  only  of  the 
lower  series  are  left  from  erosion,  and  but  one  is  possibly  of  work- 
able thickness. 

Five  miles  north,  on  the  opposite  dip,  the  seams  come 
up  on  Rock  creek  as  coking  coal ; from  here  the  outcrop  turns  to 
the  west  around  the  topographical  basin  of  Coal  creek,  caused  by 
the  protrusion  and  erosion  of  Colorado  shales,  the  coal  measure 
sandstones  dipping  outward  in  cliffs  1,000  to  2,000  feet  high.  In 
this  basin,  the  coals  are  extremely  fat,  and  produce  a hard,  bright, 
sonorous  coke. 

Going  north  from  this  disturbance  half  a mile,  the  measures 
again  dip  to  the  west  under  the  influence  of  the  fold  that  made 
the  anticlinal  valley  of  Rock  creek  and  Roaring  Fork,  and  con- 
tinue so  for  twenty-three  miles  northward  to  the  Grand  river,  at 
an  average  pitch  of  45  °,  and  as  a ridge  a thousand  feet  higher 
than  the  parks  of  the  Colorado  shales  to  the  east.  This  stretch 
of  outcrop,  intrinsically  a most  valuable  part  of  the  field,  is  cut 
by  three  streams  that  can  be  used  by  railway  lines,  viz:  at  six 
miles  from  the  basin  by  one  fork  of  Thompson  creek;  one  mile 
further  by  another;  and  six  miles  further  by  Four  Mile  creek. 
All  these  gaps  have  an  altitude  of  about  8,000  feet,  necessitating 
eight  or  ten  miles  of  four  per  cent,  grade  to  get  up  to  them  from 
the  Roaring  Fork  valley  K whose  altitude  is  about  6,000  feet. 
About  opposite  Glenwood  Springs  in  the  Newcastle  district  the 
measures  come  under  the  influence  of  the  great  uplift  of  the 
White  river  plateau  to  the  north,  around  which  they  describe  a 
wide  circle  for  sixty-nine  miles,  and,  standing  at  50°  to  90°,  are 
known  as  the  great  Hogback.  In  that  distance  the  coal  measures 
are  accessible  at  eight  gaps;  but  the  conditions  have  nowhere 
been  such  as  to  produce  coking  coal. 

Sixteen  miles  northeast  of  the  White  River  gap,  at  Meeker, 
under  the  erosion  of  the  Yampa  valley,  the  outcrop  has  lost  the 
influence  of  the  plateau,  and  is  flat,  with  a western  direction  for 
thirty-two  miles.  Here  the  influence  of  the  Blue  Mountain  is 
felt,  and  the  outcrop  is  bent  to  the  south  for  twelve  miles  to  the 
White  river;  then  it  follows  the  foot-hills  as  a hogback  to  the 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


205 


State  line  a distance  of  thirty-four  miles  in  a westerly  course  with 
but  two  gaps.  Near  the  State  line  and  just  south  of  this  hog- 
back on  White  river,  at  the  mouth  of  Douglas  creek,  there  is  an 
upheaval  similar  to  that  of  Coal  Basin,  but  of  less  violence,  and 
without  the  conditions  to  change  the  character  of  the  coal  from 
dry  to  coking. 

The  geographically  valuable  parts  of  this  200  miles  of  out- 
crop are  the  eastern  and  western,  and  most  of  the  intrinsically 
valuable  coal  is  in  the  southern  ten  or  fifteen  miles. 

The  southern  outcrop  of  this  field  begins  on  the  headwaters 
of  the  north  fork  of  the  Gunnison,  a few  miles  west  of  Coal 
Basin,  where  the  beds  are  flat  and  the  erosion  great ; thence  fol- 
lowing that  river,  receding  as  it  falls,  it  crosses  the  Grand  fifteen 
miles  above  the  confluence  and  takes  its  direction  into  Utah. 

In  this  field,  as  elsewhere  in  the  State  the  Halymenites 
Fucoidal  sandstone  is  the  only  datum  that  approaches  persis- 
tency. It  varies  from  a compact,  hard  white  sand  rock  to  a 
coarse  sandy  shale,  and  over  thirty  miles  of  the  southeastern  out- 
crop the  fossil  bed  on  top  of  it  is  quite  persistent.  But  it  is  not 
always  the  base  of  the  coal  measures.  At  one  place,  west  of 
the  Grand,  there  are  two  workable  coal  seams  below  it. 
In  fact  all  the  measures  of  the  section  lack  persistency  and  except 
a liability  of  recurrence  of  two  heavy  sandstones  enclosing  the 
upper  series  of  beds,  a section  in  one  gulch  shows  no  resem- 
blance to  the  next  one  a couple  of  miles  away.  There  is  no  lime- 
stone in  the  measures,  though  many  of  the  sandstones  are 
impregnated  with  lime  and  gypsum. 

The  150  to  200  feet  of  sandstones  and  shales  above  the  Hal- 
ymenites sandstone  always  contain  two  and  often  three  or 
four  workable  seams  and  occasionally  two  or  more  come  together 
and  form  a large  and  usually  dirty  seam. 

Thorough  prospecting  on  ten  miles  of  outcrop  north  of 
Thompson  creek,  has  shown  that  no  seam  remains  workable  in 
size  a greater  distance  than  two  miles,  and  usually  not  half  that 
distance.  All  the  seams  except  one,  and  that  worthless,  are 
nearly  as  variable  in  character  and  marking  as  in  size.  These 
facts,  with  a cross  faulting  every  4000  to  6000  feet  of  from  30  to 
275  feet,  make  it  difficult  to  say  which  of  these  beds  are  main 


206 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


seams  and  which  splits.  Whether  the  upper  part  of  the  measures 
should  be  divided  is  not  certain.  In  many  places  there  are  two 
distinct  horizons  at  which  seams  recur,  but  at  three  points  of 
economical  importance,  considerable  prospecting  disclosed  but 
one,  at  600  feet  above  the  lower  series.  Development  there 
shows  that  this  series  is  more  irregular  and  patchy  than  the  lower 
one. 

It  seems  altogether  probable  that  the  break  throwing  up  the 
outcrop  occurred  near  the  margin  of  the  original  field  of  deposi- 
tion, because  the  size  and  number  of  the  measures  is  greater 
where  the  erosion  has  been  further  from  that  line. 

All  the  seams  are  coking  coal,  from  Coal  Basin  north  twelve 
miles,  or  about  six  miles  either  way  from  a point  opposite  to 
Sopris  peak,  six  miles  distant,  and  the  termination  of  the  Elk 
Mountains,  a spur  of  the  main  range.  This  peak  has  an  altitude 
of  1 2.800  feet,  it  is  an  eruptive  outbreak,  the  center  of  four  radia- 
ting anticlinal  valleys,  and  the  heat  from  it  may  have  been 
directly  or  indirectly  the  cause  of  the  coking  quality  of  the  coal 
seams,  they  are  certainly  most  “ fat  ” immediately  opposite  it,  and 
around  the  coal  basin  upheaval.  Also  the  lower  coals  are  the 
fatter. 

On  the  northern  edge  of  this  influence  half  a mile  of  devel- 
opment shows  a gradual  change  from  a good  coking  coal  to  a 
dry  coal  that  with  ordinary  bee-hive  treatment  will  barely  agglu- 
tinate. In  another  half  mile  the  same  seam  is  dry.  In  this 
transition  area,  a small  cross  fault  makes  the  coal  “ fat  ” for 
twenty  or  more  feet  on  either  side.  The  dry  seams  also  present 
wide  chemical  and  physical  changes  in  short  distances  ; a soft  and 
loosely  bedded  coal  has  in  100  feet  become  compact  and  hard 
without  the  intervention  of  a fault.  A couple  of  hundred  feet 
has  reduced  the  water  combination  from  twelve  to  five  per  cent. 
In  seams  of  coal  free  from  binders  of  slate  or  bony  coal,  the 
squeezing  during  upheaval  has  obliterated  the  cleavage  and  often 
the  bedding.  The  floor  and  roof  of  the  seams  are  generally 
more  or  less  of  shaly  clay  slate  that  slacks  and  crumbles  on 
exposure.  These  facts,  together  with  a steepness  of  dip  make 
mining  difficult ; and  extensive  development  will  demand  the 
modification  of  any  system  now  in  use  in  the  United  States.  ” 


CHAPTER  XI. 


Geology  Between  Gunnison 
City  and  Ouray. 


Chapter  XI. 

DESCRIPTION  OF  GEOLOGY  BETWEEN  GUNNISON 
CITY  AND  OURAY. 

From  Gunnison  City  we  go  by  train  to  Ouray.  The  region 
about  Gunnison  City  as  we  go  west  is  characterized  by  table 
lands  and  plateaus,  most  of  them  capped  by  lava  or  volcanic 
breccia  which  rest  sometimes  directly  on  upturned  granite  and 
sometimes  on  relics  of  Cretaceous  strata  that  once  covered  the 
granite  but  have  been  largely  removed  by  erosion. 

Between  Gunnison  City  and  Sapinero  station  on  the  Denver 
& Rio  Grande  railroad,  we  enter  a canon  through  several  hun- 
dred feet  of  variegated  marls  and  shales  resting  on  the  granite. 
The  series  is  capped  by  some  300  feet  of  volcanic  breccia  over- 
laid by  a hundred  feet  or  more  of  lava  in  two  flows  or  sets  of 
pillars.  In  the  marls  and  shales  are  some  dark  lines  which  may 
indicate  the  presence  of  coal. 

This  short  canon  is  an  introduction  to  the  noted  Black  Canon, 
one  of  the  most  picturesque  in  Colorado,  which  we  presently 
enter.  The  walls  are  of  massive  jointed  granite  and  bedded 
gneiss.  The  bedding  and  other  characters  did  not  seem  to  us 
quite  to  correspond  on  either  side,  and  if  this  be  the  case  the 
origin  of  the  canon  may  have  been  along  a line  of  fault,  the  rest 
being  the  work  of  erosion.  The  celebrated  Curricanti  needle  so 
often  seen  in  pictures  and  photographs,  is  a pyramid  or  obelisk  of 
granite  separated  from  the  main  mass  by  the  erosion  of  two  side 
canons.  The  canon  is  cut  down  deep  beneath  the  horizontal 
table  lands  of  the  region  and  is  like  a great  rift  below  the  lava- 
covered  surface  of  the  country.  The  entire  region  between  Gun- 
nison and  Lake  City  is  a monotonous  plain  of  lava  covered  with 
sage  bush  with  occasional  outcrops  of  granite  breaking  through 
the  surface  of  the  once  molten  crust.  From  the  scoriaceous, 
vesicular  character  of  this  lava  it  would  appear  to  have  been  a 
surface  flow. 


210 


GEOLOGY  OF  COLORADO  COAL  FIELDS, 1 


At  Cimarron  station  we  emerge  from  the  canon  to  find  the 
drab  shales  of  the  Fox  Hills  Cretaceous  resting  upon  and  dip- 
ping off  from  the  Archean  granite  in  a westerly  direction,  and 
thence  to  near  Ouray  we  meet  only  with  the  Cretaceous  formations. 

The  entire  absence  of  the  older  groups  and  the  direct  super- 
position of  the  Cretaceous  upon  the  Archean  granite  in  contrast 
to  what  we  find  on  the  eastern  border  of  the  mountains,  where 
older  strata  generally  intervene,  seems  to  imply  that  this  portion 
of  Colorado,  for  an  indefinite  distance  into  Utah,  was  above  the 
ocean  as  a granite  island  or  continental  mass  during  the  whole  of 
those  earlier  periods  when  seas  were  depositing  various  sediments 
along  the  more  eastern  border  of  the  present  ranges,  and  that  it 
was  not  until  the  Cretaceous  period  that  by  a probable  subsidence 
of  the  region,  the  Archean  land  was  sufficiently  submerged 
beneath  the  waves  to  admit  of  its  being  covered  by  Cretaceous 
sediments. 

The  uplift  since  that  period  does  not  seem  in  this  western 
part  to  have  been  so  great  or  violent  as  along  the  eastern  border, 
the  beds  being  at  a gentler  dip  which  soon  passes  into  horizon- 
tally, giving  rise  to  the  prevailing  plateau  character  which  extends 
west  as  far  as  the  eye  can  reach. 

We  descend  gradually  into  the  country  of  drab  and  yellow 
shales  towards  the  valley  of  the  Uncompahgre  river,  and  at  Mon- 
trose take  a branch  line  to  Ouray,  following  the  course  of  that 
river  to  its  exit  from  the  volcanic  San  Juan  mountains,  which  rise 
above  the  monotonous  plateau  country  in  snow  capped  towers 
and  terraced  battlements,  a few  miles  to  the  south.  As  we 
approach  them  the  influence  of  their  disturbance  and 
uplift  becomes  apparent  in  the  gradual  steepening  of  the  dip  of 
the  sedimentary  strata.  Between  Dallas  and  Ouray  we  meet  the 
characteristic  yellow  sandstone  of  the  Laramie  group  resting 
upon  the  Foxhill  shales  and  can  see  them  stretching  away  like  a 
girdle  around  the  flanks  of  the  San  Juan  mountains,  attaining  a 
thickness  of  over  i ,000  feet,  the  upper  section  of  which  may  possi- 
bly be  Tertiary.  The  lavas  and  breccias  of  he  San  Juan  appear  in 
the  distance  to  cap  this  formation.  Indications  of  coal  appear  at 
the  usual  horizon  above  the  basal  sandstone,  and  some  prospect- 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


2 1 1 


ing  appears  to  have  been  done,  but  so  far  as  we  could  learn  with 
no  satisfactory  results.  The  coal  seams  are  said  to  be  very 
narrow. 

As  we  ascend  the  stream  the  uplift,  combined  with  erosion 
brings  lower  strata  successively  into  view.  Beneath  the  Laramie 
appear  the  Foxhills  and  Dakota  Cretaceous,  followed  by  the  Red- 
beds  of  the  Jura-Trias,  which  latter  appear  to  be  thrown  into  two 
or  more  synclinal  and  anticlinal  folds,  and  below  these  again  are 
thick  massive  strata  of  brownish  red  conglomerate  and  paler  belts 
of  sandstone  and  limestone,  belonging  to  the  upper  and  middle 
Carboniferous,  with  limestones  at  the  base  probably  Lower  Car- 
boniferous. All  these  groups  of  strata,  together  with  the  still 
lower  Silurian  and  Cambrian  quartzite  and  Archean  granite,  are, 
as  we  enter  the  mountains  covered  with  prodigious  volumes  of 
volcanic  breccia  and  other  lavas  to  a thickness  of  from  3,000  to 
5,000  feet,  forming  the  San  Juan  mountain  system,  the  individual 
peaks  and  castles  resulting  from  the  erosion  of  profound  valleys 
and  canons  out  of  a once  lava  deluged  plateau. 

A narrow  canon  leads  us  to  Ouray,  the  most  picturesquely 
situated  town  in  Colorado,  located  in  a deep,  wide  pit  or  amphi- 
theater in  these  mountains.  This  is  hollowed  out  of  the  volcanic 
cap  and  underlying  Paleozoic  strata  by  glacier  and  stream.  The 
massive  layers  of  strata  rise  tier  upon  tier  in  the  almost  vertical 
cliffs  surrounding  the  town,  which  are  capped  by  the  volcanic 
breccia.  They  are  traversed  by  igneous  dykes  and  horizontal 
sheets  of  lava  welding  the  strata  together  as  by  iron  girders. 

One  of  these  dykes,  of  a greenish  porphyritic  character,  is 
seen  on  the  walls  of  the  canon  as  we  enter,  sending  out  from  it 
intrusive  sheets  of  lava  between  the  strata,  while  on  top  of  all 
rests  the  massive  sombre  gray  volcanic  breccia.  The  bulk  of  this 
display  of  red  and  white  quartzite,  conglomerate  and  limestone, 
appears  to  belong  to  the  Carboniferous,  the  upper  portion  of  it 
may  be  Trias.  Near  the  northern  entrance  of  the  canon  what  is 
supposed  to  be  the  Dakota  group  metamorphosed  into  quartzite, 
carries  in  irregular  cavities  between  the  bedding  planes  and  joints 
which  have  been  enlarged  by  the  action  of  water,  quantities  of 
sand  and  gravel  containing  considerable  free  gold,  which  has 
giyen  rise  to  the  recent  gold  excitement  on  what  has  been  called 


212 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


“The  gold  belt  of  Ouray.”  Intrusive  sheets  of  porphyrite  lie 
above  this  quartzite  with  feeding  dykes  running  up  to  them,  the 
whole  being  capped  by  remnants  of  the  volcanic  breccia.  The 
location  of  the  “gold  belt”  with  the  openings  upon  it  are  in 
plain  view  from  the  city,  upwards  of  1000  feet  high  on  the  cliff 
near  the  northern  entrance  to  the  town. 

THE  OURAY  HOT  SPRINGS. 

Ouray  has  long  been  noted  for  its  hot  springs.  They  are 
located  towards  the  upper  end  of  the  town  at  the  base  of  the  ver- 
tical cliffs,  and  issue  from  the  limestone.  The  water  is  about 
128°  Fahrenheit.  A flat  terrace  above  the  springs  covering  sev- 
eral acres,  on  which  the  upper  part  of  the  town  is  built,  is  com- 
posed of  layers  of  spongy  calcareous  tufa  some  thirty  to  fifty  feet 
thick,  honeycombed  with  little  cavities,  and  full  of  traces  of  com- 
paratively recent  fossil  vegetation.  This  shows  the  former  con- 
tinuous action  of  the  hot  springs  on  a larger  scale  and  over  a 
much  greater  area  than  at  present.  The  tufa  is  matter  deposited 
by  the  springs  derived  from  the  underlying  limestone.  Swim- 
ming baths  are  established  at  the  springs,  and  apart  from  its  min- 
ing interests  this  pretty  town,  with  its  villas  and  fine  hotels,  has 
quite  the  air  of  a watering  place. 

From  Ouray  we  enter  the  heart  of  the  San  Juan  mountains 
through  the  canon  of  the  Uncompahgre  river  by  the  Mears  road, 
which  is  a wonderful  feat  of  engineering.  The  road  is  hewn  for 
several  miles  out  of  the  hard  vitreous  quartzite  along  the  face  of 
a vertical  cliff  looking  down  a thousand  feet  upon  the  boiling 
torrent  in  the  bottom  of  the  canon.  As  we  ascend  the  pass 
the  Carboniferous  limestones  are  succeeded  by  an  enormous 
thickness  of  13,000  feet  of  distinctly  stratified  quartzites,  slates 
and  schists.  Part  of  these  may  belong  to  the  Silurian  and  Cam- 
brian series,  but  as  these  series  combined  rarely  attain  in  Colo- 
rado, a thickness  of  1,000  feet,  so  great  a body  at  this  locality  is 
extraordinary,  and  to  account  for  it,  it  has  been  suggested  that 
part  of  it,  i.  e.  the  lower  portion  may,  as  in  Canada,  belong  to  the 
Huronian  or  Laurentian,  upper  divisions  of  the  Archean  not  else- 
where represented  in  Colorado.  The  dip  of  these  quartzites  is 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


213 


about  750  and  to  the  north.  Their  uplifted  crests  have  been 
deeply  eroded,  and  in  the  hollows  so  formed  rest  the  massive 
volcanic  breccias  for  a thickness  of  from  2,000  to  5,000  feet. 

It  is  evident  that  the  eruption  of  these  lavas  must  have 
occurred  not  only  after  the  formation  of  these  Paleozoic  beds  but 
also  after  they  were  uplifted  into  mountain  forms.  As  we  find 
strata  of  all  ages  even  to  the  supposed  Tertiary,  covered  by  the 
eruptive  rock,  we  may  infer  that  some  of  these  eruptions  occurred 
after  or  during  Tertiary  times. 

The  breccia  is  composed  of  angular  blocks  of  lava  of  all 
sizes  and  generally  of  an  olive  green  or  pinkish  blue  cemented 
together  by  a paste  of  the  same  material.  These  lava  caps  are 
traversed  by  great  numbers  of  large  quartz  fissure  veins  running 
in  parallel  systems  usually  carrying  more  or  less  mineral  and 
yielding  the  principal  metallic  wealth  of  the  district. 

All  the  way  up  the  canon  we  notice  the  effect  of  the  glacier 
that  once  filled  it,  in  the  smooth  rounded  outlines  of  some  of  the 
rocks  that  formed  its  bed,  as  well  as  in  the  numerous  parallel 
scratches  or  striae  left  on  the  hard  vitreous  quartzite. 

We  arrive  at  last  at  the  head  of  the  gorge,  climb  over  a steep 
bench  and  find  ourselves  in  a flat  meadow-bottomed  valley  lead- 
ing to  Ironton.  In  this  valley  are  numerous  swamps  and  ponds, 
the  bottoms,  weeds  and  floating  timber  of  which  are  thickly 
incrusted  with  bog  iron.  The  source  of  this  iron  is  the  pyrites 
and  other  iron  bearing  minerals  with  which  the  lavas  are  charged. 
The  oxidation  of  this  iron  has  painted  the  rocks  of  the  sur- 
rounding mountains  with  brilliant  orange,  and  vermillion  and 
maroon  colors  and  given  the  name  of  Red  mountain  to  a partic- 
ularly gorgeous  locality.  There,  as  well  as  at  Ironton,  large  min- 
ing operations  are  carried  on  upon  silver  bearing  fissure  veins, 
the  ore  not  unfrequently  being  found  in  a series  of  small  caverns 
in  the  quartz  veins.  From  Ironton  a train  carries  us  through  the 
finest  scenery  in  Colorado  to  Silverton  and  thence  down  the  Ani- 
mas canon  to  Durango  where  as  we  have  narrated,  the  great 
southwestern  coal  fields  are  to  be  seen.  Thus  we  completed 
the  circle  and  the  grand  tour  of  Colorado’s  principal  coal  fields. 


CHAPTER  XII. 


The  Park  Coal  Fields. 


Chapter  XI J 

THE  PARK  COAL  FIELDS. 

Large  bodies  of  coal  are  to  be  found  in  the  South  and  North 
parks,  which  may  be  called  isolated  fields  as  they  are  cut  oft 
from  the  main  fields  by  encircling  mountains. 

These  “ parks,”  as  they  are  called,  are  a characteristic  feature 
of  the  topography  of  Colorado.  They  are  in  reality  broad  val- 
leys occupying  lines  of  depression  between  different  ranges  ol 
mountains,  and  owe  their  origin  partly  to  geological  structure 
and  great  geological  movements,  and  partly  to  erosion.  As  the 
geology  of  thesfe  parks  involves  many  of  the  main  features  of  the 
geological  structure  of  the  Rocky  Mountain  system,  we  will 
quote  in  explanation  Mr.  Emmon’s  concise  description  of  the 
general  geology  of  these  mountains.  He  says,  in  the  census 
report  of  the  Geological  Survey  : 

“ The  mountain  belt  of  Colorado,  which  in  this  latitude  is 
generally  known  as  the  Rocky  Mountains,  to  distinguish  it  from 
the  other  principal  Cordilleran  systems  to  the  westward,  the 
Wahsatch  and  the  Sierra  Nevada,  has,  taken  as  a whole,  a due  north 
.and  south  trend.  When  examined  in  detail,  however,  it  is  found 
to  be  made  up  of  a number  of  more  or  less  regular  chains  or 
ridges  having  a general  trend  to  the  west  of  north,  standing  “ en 
echelon  ” or  with  their  ends  overlapping  each  other,  with  moun- 
tain valleys  of  greater  or  less  extent  between  them,  as  the  result 
of  which  structure  the  mountains  in  general  seem  to  be  divided 
up  into  two  chains,  with  large  included  valleys  which  have  received 
the  name  of  “ Parks.” 

The  general  name  of  Colorado,  or  Front  range  has  been 
given  to  the  eastern  of  these  divisions,  and  that  of  Park  range  to 
the  western.  The  North,  Middle  and  South  parks  and  the  San 
Luis  valley  are  the  larger  of  the  included  valleys,  the  three 
former,  with  the  smaller  Wet  Mountain  valley  to  the  south,  being 


2[8 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


really  a portion  of  the  same  continuous  line  of  depression,  while 
the  valley  of  the  Upper  Arkansas  stands  in  the  same  relation  to 
the  San  Luis  valley. 

The  eastern  front  of  this  range  presents  a comparatively  regular 
north  and  south  line,  broken  here  and  there  by  baydike  valleys, 
running  up  into  the  mountains  in  a northwesterly  direction  and 
following  the  prevailing  trend  of  the  echelon  ridges.  The  most 
important  of  these  are  the  Manitou  and  Huerfano  parks,  and 
that  which  extends  up  Oil  creek  from  Canon  City.  These  in 
earlier  geological  times  were  actual  bays  in  the  seas  in  which  the 
Paleozoie  and  Mesozoic  rocks  were  deposited,  while  the  parks 
were  partially  inclosed  arms  of  those  seas. 

The  western  front  of  the  mountains  is  more  irregular  and  is 
broken  by  branching  mountain  groups  extending  out  also  with  a 
general  northwest  trend  into  the  ‘ Mesa  ’ country  of  the  Colorado 
plateau.  The  principal  of  these  outlying  mountain  groups,  com- 
mencing on  the  north,  are  the  Elk  Head  mountains,  the  White 
River  plateau,  the  Elk  mountains,  and  the  San  Juan  mountains, 
in  all  of  which  there  is  a very  great  development  of  eruptive 
rocks.”  The  geological  history  is  as  follows  : “ At  the  close  of 

the  Archean  era,  or  in  the  Cambrian  ocean,  a large  area  covering 
most  of  what  is  now  the  Colorado  or  Front  range,  formed  a large 
rocky  island  with  a number  of  smaller  islands  lying  to  the  west- 
ward, the  most  important  of  which  now  forms  the  Sawatch,  from 
which  it  was  more  or  less  completely  separated  by  the  waters 
occupying  the  present  depressions  of  the  North,  South  and  Mid- 
dle Parks. 

During  the  whole  of  the  Paleozoic  and  Mesozoic  eras,  a con- 
tinuous sedimentation  went  on  in  the  seas  surrounding  these 
islands,  of  material  derived  from  the  abrasion. 

The  geological  record  gives  evidence  of  no  great  disturbance 
during  this  long  period.  Toward  the  close  of  the  Cretaceous 
period  at  the  time  of  the  formation  of  the  coal  beds,  the  seas 
became  shallower  owing  to  a general  elevation  of  land  and  con- 
siderable portions  of  the  outlying  areas  were  partially  inclosed. 
During  this  time  and  possibly  earlier,  immense  masses  of  erup- 
tive rock  were  forced  up  through  the  already  deposited  sediments 
which  were  still  beneath  the  water.  Unlike  the  lava  flows  of 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


219 


modern  days  however,  these  molten  masses  were  not,  as  a rule, 
spread  out  on  the  surface  of  the  rocks,  but  congealed  before  they 
reached  it,  either  in  large  masses,  in  dykes,  or  in  sheets  forced  in 
and  spread  out  between  the  beds.  These  eruptions  seem  to  have 
continued  nearly  to  the  close  of  the  Cretaceous  period. 

At  some  time  after  the  close  of  the  Cretaceous  period  a 
general  dynamic  movement  took  place  in  the  Rocky  Mountains, 
by  which  the  existing  mountain  ranges  or  islands  were  crushed 
together,  broken  and  elevated,  and  considerable  areas  of  the 
adjoining  sea  bed  were  lifted  above  the  surface 

In  the  general  continental  elevation  which  followed  fresh- 
water lakes  or  inclosed  seas  were  formed  in  which,  by  the  degra- 
dation or  wearing  away  of  the  newly-made  land  areas,  considerable 
sediments  were  deposited.  The  outline  of  these  Tertiary 
seas,  owing  to  the  nature  of  the  deposits  made  in  them,  which 
were  easily  eroded  and  carried  away  by  subsequent  atmospheric 
agencies,  cannot  be  yet  definitely  determined.  It  can  only  be  said 
that  their  area  and  location  were  frequently  changed,  and  that 
during  the  Tertiary  era  and  subsequent  to  it,  eruptions  of  igneous 
rock  occurred,  generally  following  the  lines  of  earlier  eruptions,  but 
unlike  those,  spreading  out  on  the  actual  surface  of  the  land,  and 
in  some  cases  beneath  the  sea. 

While  the  general  form  of  the  mountain  area  as  has  been 
shown  was  determined  in  the  very  earliest  geological  times,  it  is 
only  since  the  Tertiary  era,  and  in  a great  measure  by  erosion  sub- 
sequent to  the  Glacial  era  that  the  present  sculpturing  of  the 
mountain  forms  and  carving  of  the  valleys  have  taken  place.” 

THE  SOUTH  PARK. 

It  is  a pleasant  change  and  surprise  after  a day’s  ride  up  the 
Platte  canon,  through  fifty  miles  of  Archean  granite  and  gneiss 
of  the  Colorado  range,  to  reach  the  brow  of  a hill  and  look  down 
into  the  prairie  basin  of  South  Park,  encircled  with  snow- 
capped mountains.  The  South  Park  is  an  oval  basin  about  forty 
miles  long  by  twenty  miles  broad.  The  general  surface  is  varied 
by  a series  of  parellel  crescentic  ridges  or  hogbacks,  composed 
of  the  strata  forming  its  floor,  tipped  up  on  all  sides  except  the 
east  by  the  elevation  of  the  encircling  mountains. 


220 


GEOLOGY  OF  COLORADO  COAL  LI  ELDS. 


Parallel  with  these  “hogbacks,”  or  sometimes  crossing  them 
diagonally,  are  other  steep  ridges  and  “buttes”  of  brown  eruptive 
rock  which  issued  from  fissures  now  occupied  by  dykes. 

The  crescentic  axes  of  elevation  form  a quaquaversal  of  the 
strata,  dipping  generally  towards  a common  centre,  which  lies 
toward  the  eastern  portion  of  the  park  and  which  is  more  or  less 
horizontal. 

The  basin  so  formed  is  not  complete  on  the  east  side,  nor  so 
far  as  known  do  the  strata  tip  up  there  as  we  should  expect  them 
from  the  elevation  of  the  Front  range. 

The  explanation  of  this  may  be,  the  existence  of  a fault  run- 
ning along  the  eastern  part  caused  by  the  strata  in  the  process 
of  elevation  being  broken,  and  slipping  down  from  the  granite  ; 
proofs  of  this,  however,  are  obscured  by  drift  and  vegetation. 

The  valley  plains  are  covered  by  sedimentary  strata  of  Meso- 
zoic age,  which,  with  the  underlying  and  conformable  Paleozoic 
formations,  slope  up  to  the  crest  of  the  Mosquito  range  on  the 
west.  Some  of  these  strata  even  cap  the  top  of  the  highest  moun- 
tains of  Colorado,  such  as  Silverheels  and  Mt.  Lincoln.  The 
former  with  red  Trassic  sandstone,  the  latter,  over  14,000  feet 
high,  with  Carboniferous  limestone.  Thus  part  of  what  was  once 
the  floor  of  the  park  by  upheaval  along  its  edges  has  become  the 
summit  of  its  encircling  range,  and  what  was  once  the  bottom  of 
a primeval  sea  with  its  entombed  sea  shells  has  been  elevated  to 
the  top  of  the  highest  mountains,  and  the  whole  strata  of  the  park 
itself  have  been  raised  bodily  4,000  feet  above  the  position  of  the 
same  strata,  belonging  to  the  same  time  of  formation  on  the 
great  plains,  for  the  average  altitude  of  the  South  Park  is  10,000 
feet  above  the  sea  level,  while  that  of  the  plains  is  between  5,000 
and  6,000.  It  is  thus  a fragment  of  the  great  plains  and  prairie 
caught  up  is  the  embrace  of  the  rising  mountains  and  lifted 
bodily  to  a height  of  5,000  feet  above  them. 

The  geological  history  of  the  North,  Middle  and  South  parks 
is  briefly  that  they  were  submerged  in  Paleozoic  and  Mesozoic 
times  by  the  sea  and  at  a later  period,  viz:  in  Tertiary  times  by 
fresh  water  lakes.  They  formed  a connected  series  of  bays  and 
arms  of  the  sea  and  afterwards  of  fresh  water  lakes  as  shown  by 
the  succession  of  marine  and  fresh  water  sediments  found  in  them. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


221 


“ In  Paleozoic  times  the  outlet  of  the  sea  of  the  North  Park 
was  towards  the  north,  of  the  Middle  Park  toward  the  west,  and 
of  the  South  Park  toward  the  south.  Up  to  the  close  of  the 
Cretaceous,  the  North  and  Middle  parks  were  connected  form- 
ing a single  depression.  The  present  mountain  barrier  between 
the  Middle  and  South  parks  did  not  extend  as  far  as  their  western 
boundaries  and  a water  connection  lay  between  them.”  Proof  of 
this  we  find  in  narrow  patches  of  sedimentary  rock  lying  along 
the  valley  of  the  Blue  river  beyond  Breckenridge  which  connects 
the  parks  together. 

The  waters  of  the  South  Park  in  Paleozoic  times  extended 
westward  to  the  flanks  of  the  Sawatch  range,  the  present  inter- 
vening Mosquito  range  not  then  existing,  it  having  been  lifted  up 
later  in  the  Cretaceous.  In  Tertiary  times  the  peaks  had  been 
raised  sufficiently  above  the  ocean  level  to  be  occupied  by  great 
fresh  water  lakes  bounded  on  the  west  by  two  ridges  or  islands 
parallel  with  the  Front  range,  viz  : the  Park  range  proper  on  the 
west  side  of  North  Park,  and  the  Sawatch  range  now  separated 
from  the  South  Park  by  the  Mosquito  range  but  practically  a 
continuation  of  the  Park  range,  while  between  the  Sawatch  and 
Park  ranges  lay  the  granitic  Gore  range  forming  with  portions 
of  the  Park  range  the  western  wall  of  Middle  Park. 

In  the  period  intervening  between  the  close  of  the  Cretaceous 
and  the  laying  down  of  the  Tertiary  strata  during  which  the 
waters  of  the  ocean  were  gradually  receding  from  the  Rocky 
Mountain  region  and  permitting  coal  beds  to  form  in  marshes 
from  peat  and  land  vegetation,  the  pent  up  forces  of  contraction 
in  the  earth’s  crust  which  had  long  been  accumulating,  found 
expression  in  dynamic  movements  of  the  rocky  strata,  pushing 
together  from  the  east  and  west  the  more  recent  stratified  rocks 
against  the  relatively  more  rigid  masses  of  the  Archean  granitic 
land  and  thus  folding  and  crumpling  the  beds  in  the  vicinity  of 
the  shore  lines.  So  were  these  shore  line  strata  crumpled  up  to 
form  the  Mosquito  range,  constituting  the  present  western  boun- 
dary of  South  Park. 

These  ranges  were  not  uplifted  by  an  up-thrust  from  below, 
but  by  horizontal  tangential  pressure  resulting  from  contraction 
of  the  earth’s  crust  caused  by  the  cooling  of  its  interior.  This  is 


222 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


shown  in  the  folded  character  of  the  rocky  masses  and  as  the 
forces  of  contraction  became  stronger,  the  folds  were  pressed 
closer  together  and  finally  broken  in  enormous  fractures  or  faults 
in  lines  parallel  to  the  trend  of  the  range  and  the  axes  of  the 
folds.  Eruptive  rocks  poured  out  in  many  places  through  the 
fissures  so  formed  and  added  to  the  mountain  masses.  Along  the 
line  of  the  Parks  both  earlier  and  later  eruptions  are  so  frequent 
as  to  form  nearly  a continuous  belt. 

The  structure  of  the  Mosquito  range  is  a typical  one.  It 
consists  of  a series  of  gigantic  compressed  folds  of  the  strata  of 
South  Park,  containing  numerous  intrusive  sheets  of  eruptive 
rock  intercalated  between  the  beds.  The  whole  mass  is  repeat- 
edly fractured  by  a series  of  faults  running  parallel  with  the  trend 
of  the  range,  and  the  axes  of  former  folds. 

Its  history  is  briefly  as  follows: 

In  the  seas  of  the  Paleozoic  and  Mesozoic  eras  that  beat 
against  the  Sawatch  island,  10,000  feet  of  sandstones,  limestones, 
conglomerates  and  shales  were  deposited.  Towards  the  close  of 
the  Cretaceous,  or  perhaps  earlier,  eruptions  occurred  beneath  the 
sea  bottom  by  which  enormous  masses  and  sheets  of  eruptive 
rock  were  intruded  through  the  Archean  floor  into  the  overlying 
sedimentary  beds  that  still  lay  beneath  the  waters,  crossing 
some  of  the  beds  and  spreading  out  in  immense  intrusive  sheets 
but  never  reaching  the  surface.  The  great  uplift  followed,  crump- 
ling up  and  faulting  the  strata  with  their  included  sheets  of  erup- 
tive rock  and  raising  them  into  the  lofty  range  called  the 
Mosquito. 

The  South  Park  branch  of  the  Union  Pacific  railroad  enters  the 
park  on  its  northeastern  corner  and  in  its  course  passes  through 
a partial  section  of  the  Park  strata.  As  the  train  descends  from 
the  granite  of  the  Colorado  range  into  the  park  we  find  the  first 
portion  for  some  miles  horizontal  and  covered  with  glacial  drift, 
below  which  probably  lies  an  indefinite  thickness  of  Tertiary  or 
else  upper  Laramie  beds  underlaid  by  the  lower  Laramie  or  coal 
bearing  group.  The  latter  as  we  reach  Como  station  becomes 
upturned  into  a hogback  against  a heavy  mass  of  eruptive  rock 
lying  to  the  west  of  it  and  forming  the  steep  hill  back  of  the  town 
of  Como.  The  outcrop  of  the  coal  bearing  series  can  however  at 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


223 


intervals  be  followed  in  a crescentic  line  disturbed  by  dykes  and 
faults  from  Como  at  the  north  to  within  a few  miles  of  the  Mid- 
land railroad,  which  enters  the  park  near  its  southeast  corner. 
This  outcrop  makes  a bend  a few  miles  south  of  Como,  round  a 
promintory  of  granite  issuing  from  the  Colorado  range  and 
known  as  Lost  Park.  Some  of  the  coal  openings  are  situated 
close  to  Como  and  others  nearer  the  bend  of  this  promontory  in  a 
line  of  about  six  miles. 

Beyond  that  point  there  are  no  important  openings,  though 
traces  of  coal  have  been  found  as  far  south  as  a few  miles  north- 
east of  Hartzell’s  Hot  Springs.  The  borings  made  there  found 
the  coal  seam  too  narrow  to  work  and  disturbed  by  faultings  and 
the  presence  of  eruptive  dydes.  These  disturbances  seem  to  be 
the  prevailing  character  in  developing  the  coal  of  the  park  along 
its  outcrop,  but  it  is  probable  that  the  coal  would  be  found  less 
disturbed  and  more  horizontal  at  some  point  east  of  the  present 
line  of  development  if  borings  should  find  it  within  accessible 
depth  from  the  surface.  The  Laramie  group  can  generally  be 
traced  in  this  section  without  much  difficulty  by  the  presence  of 
fossil  leaves,  which  are  abundant.  West  of  the  coal  outcrop  is 
generally  a flat  valley  belonging  to  the  Colorado  and  Foxhills 
groups  of  the  marine  Cretaceous,  in  which,  of  course,  no  coal  is  to 
be  expected.  Through  the  centre  of  these  groups,  whose  thick- 
ness is  several  thousand  feet,  runs  an  enormous  dyke  of  eruptive 
rock  of  a pink  or  grey  porphyritic  lava,  showing  occasionally  a 
brecciated  character.  This  thick  dyke,  half  a mile  to  a mile  in 
breadth,  forms  a lofty  ridge  running  north  and  south  the  greater 
length  of  the  park,  constituting  the  east  bank  of  Trout  creek,  the 
opposite  timbered  bank  being  a hogback  of  the  Dakota  Creta- 
ceous sandstones.  In  the  bottom  of  the  valley,  along  Trout 
creek,  fossil  marine  Cretaceous  shells,  such  as  inoceram,  baculites, 
scaphites  and  ammonites  are  common. 

At  Garo  station  we  pass  through  the  second  promi- 
nent ridge  of  the  Park  formed  by  the  Dakota  sandstone  dip- 
ping east  450  and  find  ourselves  in  another  valley  occupied  by 
the  Platte  river.  This  valley  is  underlaid  by  the  varie- 
gated shales  and  red  sandstones  of  the  Triassic  period, 
whose  brilliant  red  hues  stain  the  banks  on  the  west 


224 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


side  of  the  stream.  The  Triassic  sandstones  are  trav- 
ersed by  a few  thin  belts  of  dark  gray  or  blackish  limestone,  in 
which,  however,  no  fossils  have  so  far  been  found.  A few  miles 
south  of  Fairplay,  along  the  banks  of  the  Platte,  among  the  red 
strata  is  a curious  local  outburst  of  Trachytic  tufa  cut  by  erosion 
into  rounded  forms  like  a flock  of  sheep.  This  patch,  from  its 
white  color  can  be  easily  seen  from  the  railroad  between  Fairplay 
and  Garo.  Not  far  from  this  we  found  some  years  ago  in  a 
series  of  shales  numerous  impressions  of  leaves  and  fossil  insects. 
The  latter  have  been  identified  by  Professor  Scudder,  and  some  of 
them  shown  to  belong  to  the  cockroach  family,  the 
earliest  discovery  known  of  this  order.  The  discovery 
was  made  in  prospecting  and  boring  for  some  thin  coal  seams 
which  outcropped  near  the  surface.  The  latter  proved  val- 
ueless, but  the  insect  discovery  was  a notable  one  for  science, 
and  led  to  a controversy  not  yet  decided,  as  to  whether  the  lower 
part  of  these  red  beds  are  Triassic  or  Permian. 

From  this  west  bank  of  the  Platte  a broad  flat  plateau  extends 
to  the  foot  of  the  Mosquito  range  underlaid  by  tilted  rocks  of 
the  Upper  Carboniferous  consisting  of  brown-red  conglomerates 
near  the  top,  and  near  the  base  a thick  series  of  shales  in  which 
occasionally  obscure  traces  of  coal  and  carbonaceous  shales  can 
be  found  which  have  so  far  proved  unproductive.  We  may  here 
say  that  experience  shows  that  as  no  coal  of  importance  is  to  be 
looked  for  either  here  or  generally  in  Colorado  below  the  Lara- 
mie group  the  coal  area  is  restricted  to  that  portion  of  the  park 
lying  east  of  the  coal  outcrop  from  Como  to  Hartzell’s  Hot 
Springs. 

We  must  leave  the  train  now  and  enter  the  Mosquito  range 
by  P'our  Mile  or  Horseshoe  canon  where  the  structure  of  this 
range  is  better  shown  in  section  than  anywhere  else  in  the  park. 
We  find' the  first  uplifted  set  of  strata  forming  the  west  slope  of 
the  range  to  be  made  of  gritty  conglomerates  and  quartzites 
known  as  the  “ Weber  grit  ” series  belonging  to  the  Middle  Car- 
boniferous. Underneath  these  comes  a thick  belt  of  dolomitic 
limestone  belonging  to  the  Lower  Carboniferous  so  productive  of 
silver  and  lead  ores,  and  below  this  again  several  hundred  feet  of 
shales  and  hard  vitreous  white  quartzites  belonging  to  the  Silu- 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


225 


rian  and  Cambrian  epochs.  The  latter  rests  on  the  upturned 
granite  which  appears  in  the  bottom  of  the  canon.  Intercalated 
between  these  various  beds  are  many  intrusive  sheets  of  white 
and  gray  porphyry,  and  as  we  go  up  the  creek  we  notice  dykes 
from  which  these  sheets  branched,  traversing  the  strata,  and 
towards  the  head  of  the  canon  leading  up  to  enormous  laccolitic 
intrusive  masses  which  by  removal  of  the  strata  that  once  arched 
over  them,  now  constitute  hoary  peaks  of  volcanic  rock.  But  by 
far  the  most  striking  feature  in  the  canon  is  evidence  of  dynamic 
force  in  the  structural  position- of  the  strata.  On  entering  we  see 
a perfect  steep  arch  as  of  masonry  constituting  Sheep  mountain 
an  illustration  of  which  is  given  in  our  “ Geology  of  Colorado 
ore  deposits.”  This  first  great  and  steep  fold  is  followed  by  a 
sharp  depression,  and  a series  of  abrupt  step-like  outlines  which 
continue  until  we  emerge  on  the  other  side  of  the  range  and  look 
down  into  the  broad  valley  of  the  Arkansas,  where  step  follows 
step  till  they  finally  pass  under  the  drift-covered  surface  of  the 
valley.  The  depressions  and  the  steps  or  notches  in  the  moun- 
tain outline  mark  a serie-?  of  faults  each  one  corresponding  to  a 
fold  like  that  still  remaining  on  Sheep  mountain.  We  see  that  as 
the  pressure  from  the  Park  side  i.  e.  the  east  crumpled  the  strata 
against  the  great  unyielding  mass  and  shore  line  of  the 
Sawatch  range  whose  majestic  peaks  appear  across  the  valley  of 
the  Arkansas  on  the  west,  the  tension  became  very  great  and  the 
folds  broke  into  a series  of  step  faults  some  of  them  having  a 
slip  of  several  thousand  feet. 

A few  spirifers  and  other  shells  are  to  be  found  in  the  lower 
Carboniferous  rocks  in  this  canon  and  in  the  Weber  shales 
some  impressions  of  Lepidodendra  and  other  Carboniferous 
vegetation.  The  part  traversed  by  the  Midland  railway  toward 
the  southern  part  of  the  park  is  principally  through  marine  Cre- 
taceous beds  of  the  F'ox  hills  and  Colorado  Cretaceous  shales 
traversed  by  dykes  of  eruptive  rock.  Sulphur  springs  issue  from 
these,  and  at  Hartzells  are  hot  springs  issuing  from  the  Dakota 
rocks,  beyond  this  the  road  traverses  the  Jura-Trias  red  beds, 
from  which  at  the  old  salt  works  issue  springs  sufficiently  saline 
to  produce  by  evaporation  commercial  salt ; gypsum  too  is  abun- 
dant. All  the  southern  part  of  the  park  is  covered  by  eruptive 


226 


GEOLOGY  OF  COLORADO  COAL  FIELDS. . 


rock,  such  as  rhyolite  and  dolerite.  Buffalo  peak,  a prominent 
castle  in  the  Mosquito  range,  is  formed  of  a great  eruption  of 
Andesite  lava  in  columnar  form,  belonging  to  the  later  series  of 
eruptions  dating  from  the  Tertiary  period.  The  mountains  sur- 
rounding the  park  show  in  their  sculpture  the  work  of  former 
glaciers,  and  the  surface  of  the  park  is  strewn  with  boulders 
brought  down  by  them  from  the  adjacent  hills. 

THE  COAL  MINES. 

The  coal  mines  in  the  Park  are  all  located  within  a short  dis- 
tance of  the  town  of  Como,  and  are  mostly  operated  by  the 
Union  Coal  Company.  The  Como  No.  i mine  is  opened  by  a 
slope  800  feet  deep  driven  on  the  dip  of  the  seam  which  pitches 
450  in  an  easterly  direction,  levels  are  driven  north  and  south 
from  the  slope  at  intervals  of  100  feet.  The  rooms  are  worked 
on  the  dip  the  coal  being  run  into  chutes  from  which  it  is  loaded 
on  cars  in  the  main  levels.  The  width  of  the  seam  is  seven  feet. 
In  1885  the  mine  produced  58,997  tons. 

“Como  No.  4 mine”  was  operated  in  1882,  but  before  long 
one  of  the  many  faults  that  trouble  this  field  was  encountered, 
and  the  coal  was  lost,  nor  was  it  found  again  by  boring,  hence 
the  mine  was  abandoned.  A similar  experience,  according  to 
Mr.  McNeil,  was  met  with  by  the  Denver  & Rio  Grande  Co.,  a 
mile  northwest  of  Como,  where  not  only  were  faults  and  obstruc- 
tions met  with,  but  a coking  plant  costing  $80,000  had  to  be 
abandoned  as  well  as  the  mine,  because  the  coal  failed  to  make 
good  coke.  A new  mine  called  “ Como  No.  5 ” has  been  opened 
of  late,  which  shows  a seam  seven  feet  thick  of  good  coal.  The 
capacity  of  this  mine  is  about  200  tons  daily. 

If  the  reader  could  have  accompanied  us  in  our  trips  he 
would  have  travelled  over  the  greater  part  of  the  mountain 
region  of  Colorado,  would  have  seen  some  of  the  grandest  of  its 
scenery,  and  while  investigating  the  principal  developed  coal 
fields,  he  would  at  the  same  time  have  seen  the  most  interesting 
and  leading  features  of  Colorado  geology  which  we  have  some- 
times gone  out  of  our  way  a little  to  describe,  endeavoring  to 
combine  a sketch  of  our  coal  fields  with  one  of  the  general  geol- 
ogy of  the  state. 


CHAPTER  XIII. 


Colorado  Cokes. 


Chapter  XIII. 

COLORADO  COKES. 

BY  PROFESSOR  B.  SADTLER,  JR. 

COLORADO  STATE  SCHOOL  OF  MINES. 

A chapter  on  Colorado  Cokes  had  best  commence,  like  its 
title,  geographically.  On  the  eastern  side  of  the  Continental 
Divide  rather  a small  proportion  of  the  enormous  acreage  of  coal 
lands  contains  coking  coal.  At  Trinidad,  south  and  west,  and  to 
some  extent  north  of  it,  the  coal  is  strongly  coking.  As  we  go 
along  the  narrow  strip  of  post-Cretaceous  reaching  northwest  to 
the  Huerfano  river,  the  coking  quality  gradually  disappears, 
through  the  different  stages  of  sintering  until  at  the  northern  ex- 
tremity of  the  field  the  coal  is  all  free  burning.  No  exact  locality 
can  be  named  as  the  dividing  line  between  the  coking  and  the 
non-coking  coals,  but  a point  east  of  the  Spanish  Peaks,  between 
the  Apishapa  and  Santa  Clara  creeks  would  mark  the  northern 
limit  of  at  least  a preponderance  of  coking  coal  veins.  I believe 
that  an  abortive  attempt  to  coke  the  South  Park  coal  in  the  neigh- 
borhood of  Como  was  also  made.  On  the  western  side  of  the 
divide  coking  coals  are  mined  and  coked  near  Durango,  and  large 
veins  exist  south,  west  and,  to  some  extent,  east  of  this  point. 
North,  in  the  valley  of  the  Gunnison,  coal  has  for  a long  time 
been  mined  and  coked  at  and  near  Crested  Butte. 

Still  further  north,  in  the  valley  of  the  Grand  river,  coke  is 
burned  at  a number  of  points  reached  by  the  Denver  & Rio 
Grande  and  Colorado  Midland  railways.  While  coal,  presumably 
coking,  exists  over  large  undeveloped  areas  in  the  northwestern 
portion  of  the  State,  it  has  not  been  mined  or  shipped  in  sufficient 
quanties  to  render  data,  as  to  coking  obtainable.  The  coals  of 
eastern  Colorado  are  all  post* Cretaceous  and  have  been,  on  that 
account,  erroneously  classed  by  many  writers  as  lignites.  While 
this  is  generally  true  as  regards  the  coal  north  of  the  Arkansas 


230 


GEOLOGY  OF  COLORADO  COAL  FIELDS . 


river,  it  is  not  only  untrue,  but  does  gross  injustice  to  the  strong, 
free  burning  coal  of  the  Canon  City  district,  and  the  semi-bitu- 
minous, sintering  and  coking  coals  of  Walsenburg,  Trinidad  and 
neighboring  points.  These  are  far  more  nearly  allied  in  their 
composition  and  economic  value  to  the  Pennsylvania  Bituminous 
coals  than  they  are  to  the  northern  Colorado  Lignites.  While  a 
number  of  theories  have  been  advanced  as  to  the  cause  of  the 
coking  power  in  coal,  the  writer  inclines  to  the  following  as  in  his 
opinion,  best  substantiated  by  facts.  That  is,  briefly,  that  it 
depends  upon  the  amount  of  bitumen  present.  This,  when 
exposed  to  the  heat  of  the  coking  process  melts  and  boils  as  its 
more  volatile  constituents  are  expelled,  leaving  among  the  por- 
tions af  woody  fibre  a solid  carbon  residue  which  cements  them 
together.  In  the  case  of  a sintering  coal  the  proportion  of  bitu- 
men would  be  insufficient,  making  the  resultant  coke  friable. 

Although  the  fixed  carbon  in  a coking  coal  is  generally  higher, 
and  the  “ volatile  combustible  ” lower,  this  is  not  a safe  index, 
as  the  precentage  of  these  two  constituents  (though  rarely)  may 
be  identical  in  two  coals,  and  the  coking  property  widely  differ- 
ent. This  could  be  attributed  to  the  fact  of  the  “ volatile  com- 
bustible ” being  in  one  case  more  largely  made  up  of  gas  or 
readily  volatile  hydro-carbons  and  the  bitumen  present  in  smaller 
proportion.  In  weathering,  coal  will  frequently  lose  the  coking 
property,  which  is  probably  due  to  the  decomposition  of  some  of 
the  oily  constitutents,  hence  no  test  of  the  coking  property  is 
final  unless  the  coal  is  sufficiently  removed  from  surface  influ- 
ences to  be  unweathered.  A convenient  method  of  making  the 
tests  is  by  placing  a common  assay  crucible  with  io  or  20 
grammes  of  the  powdered  coal,  and  tightly  covered,  (a  well  fitted 
scorifier  makes  & good  cover),  in  a hot  muffle  and  keeping  it  there 
until  luminous  flames  cease  to  appear.  If  there  is  no  muffle  con- 
venient the  crucible  may  be  placed  in  the  midst  of  coals  in  a hot 
stove.  Allow  the  crucible  to  cool  after  removing  from  the 
muffle  before  taking  off  the  lid.  If  the  contents  show  no  sign 
of  the  shape  of  the  original  particles,  are  strongly  coherent  and 
on  breaking  open  show  evidence  of  ebullition,  the  coal  may 
be  safely  considered  as  coking.  If  the  shape  of  the  original 
particles  remains  and  the  mass  is  friable,  the  coal  is  only  sinter- 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


231 


ing.  In  case  of  any  doubt  and  also  in  order  to  determine  the 
power  of  the  coke  to  withstand  a crushing  burden,  the  coking 
of  a heap  of  coal  would  be  advisable  (see  directions  for  “ burn- 
ing of  coke  in  heaps  ” in  Manuals)  rather  than  risk  the  useless 
erection  of  costly  coke  ovens,  as  is  said  to  have  been  the  case  at 
Como,  in  this  State,  where  $80,000  was  expended  for  a coking 
plant  before  the  coke  was  found  to  be  so  friable  as  to  be  useless, 
the  coal  being  only  a sintering  coal. 

Where  a large  number  of  coking  tests,  or  even  coal  analyses 
are  to  be  made,  and  an  assay  muffle  is  at  hand,  I have  found  that 
a large  number  of  fixed  carbon,  volatile  combustible  and  ash 
determinations  could  be  made  simultaneously  by  using  an  assay 
crucible  for  a 10  or  20  gramme  charge  of  coal  and  placing  in 
the  tightly  fitting  scorifier  lid  one  gramme  of  powdered  coal  for 
ash  determination.  Place  in  a hot  muffle  until  luminous  flames 
cease  to  appear,  then  remove  until  it  has  cooled  somewhat,  when 
the  scorifier  can  be  replaced  in  the  muffle  if  not  sufficiently 
burned.  The  larger  quantities  used,  if  the  scorifier  lid  fits  neatly 
so  as  to  exclude  air,  render  the  loss  of  fixed  carbon  small. 

Prof.  Geo.  C.  Tilden  has  checked  this  method  frequently 
against  the  ordinary  way  of  using  a platinum  crucible,  and  tells 
me  that  he  gets  uniformly  somewhat  higher  results  in  fixed  car- 
bon than  in  the  ordinary  method.  As,  however,  it  checks  itself 
very  well  I should  consider  it  fully  as  accurate.' 

As  the  amount  and  composition  of  the  ash  in  a coke  is  of  the 
first  importance,  I have  in  all  cases  given  analyses  of  smelter  sam- 
ple of  large  lots ; grab  samples  frequently  varying  so  much  as  to 
be  worthless.  It  is,  however,  often  desirable  to  form  an  idea  of 
what  a coke  will  run  in  ash  prior  to  its  manufacture.  When  all 
of  the  coal  from  the  vein,  and  not  merely  the  slack,  is  used  in 
coking  burning  an  approximation  may  be  obtained  as  follows: 

Take  an  average  sample  across  the  vein  and  quarter  it  down 
as  in  ore  sampling.  Analyze  sample,  and  deduct  ten  per  cent, 
from  the  total  of  ash  and  fixed  carbon  found.  This  will  give 
about  the  net  percentage  yield  of  coke.  Divide  this  into  the  per- 
centage of  ash  found  in  the  coal  sample  and  the  result  will  be  the 
probable  average  ash  in  the  coke.  An  example  may  be  useful. 
Taking  the  analysis  of  an  average  sample  of  coking  coal  as  54 


232 


GEOLOGY  OF  COL  OF  A DO  COAL  FIELDS. 


per  cent,  fixed  carbon  and  1 1 per  cent,  of  ash,  this  gives  a total 
of  65  per  cent,  as  the  theoretical  amount  of  coke.  Assuming  the 
net  practical  yield  to  be  10  per  cent,  less,  or  55  per  cent.,  the 
coke  would  contain  20  per  cent,  of  ash,  i.  e.  f^-°=20.  Compar- 
ing Prof.  Tilden’s  analyses  of  average  samples  of  coal  and  the 
smelter  averages  on  coke  from  the  same  coals,  we  find  that  this 
will  generally  give  a fair  approximation. 

The  ingredients  bearing  upon  the  commercial  value  of  coke, 
are  the  water,  sulphur,  volatile  combustible,  ash  and  fixed  carbon. 
Of  these,  the  latter  only  is  valuable,  the  first  four  being  to  a 
greater  or  less  extent  detrimental,  should  be  as  low  as  possible  in 
good  coke. 

The  water  is  present  only  in  large  quantity  when  careless  or 
ignorant  workmen  have  used  it  too  freely  in  the  quenching  of  the 

coke. 

We  can,  however,  afford  to  leave  it  out  of  our  calculations  in 
the  Colorado  cokes,  as  from  a large  number  of  analyses  at  hand, 
the  great  majority  show  less  than  1 per  cent,  of  water.  The  few 
cases  where  it  exceeds  this  amount  are  from  new  plants  and 
doubtless  attributable  to  the  inexperience  of  the  workmen,  which 
time  would  remedy.  If  water  were  present  in  large  quantity  it 
would  materially  lessen  the  heating  power  of  the  coke. 

The  volatile  combustible  would,  if  present  in  at  all  large  quan- 
tity, cause  the  coke  to  shatter  in  a blast  furnace.  For  this  reason 
gas- cokes  are  not  used  in  such  work;  the  bitumen  being  not 
entirely  driven  off  in  the  retorts.  This  point  we  can  also  afford 
to  disregard  as  in  none  of  the  analyses  at  hand  is  it  present  in 
dangerously  large  amounts.  The  few  containing  an  appreciable 
quantity  are,  as  above  stated,  from  new  works. 

The  sulphur  in  coke  occurs  mainly  when  iron  pyrites  is  pres- 
ent with  the  coal,  and  its  presence  is  probable  when  analysis  or 
color  of  the  ash  shows  an  unusually  large  percentage  of  iron. 
While  detrimental  in  iron  smelting,  it  is  not  present  in  sufficient 
quantity  to  make  much  difference  in  lead-silver  or  copper-silver 
smelting ; the  highest  determination  given  me  of  any  Colorado 
cokes  being  1.35  per  cent.  In  fact,  most  Colorado  cokes  are 
quite  low  enough  in  sulphur  for  use  in  iron  smelting. 

The  constituent  which  cuts  a real  and  considerable  figure  in 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


233 


all  Colorado  cokes,  is  the  ash,  which  is  with  few  exceptions  high. 
When  the  ash  of  a coal  or  coke  is  only  such  as  would  result  from 
the  condensation  of  the  plant  ash  of  the  coal-bearing  flora,  it 
should  rarely  exceed  6 per  cent,  in  the  coal  or  10  per  cent,  in  the 
coke.  A lower  ash  than  this  is  called  normal,  and  is  in  metallur- 
gical work  considered  as  self-fluxing. 

When  the  ash  exceeds  these  figures  it  is  generally  siliceous 
and  may  result  from  a failure  to  sort  out  the  slate  cleanly,  or 
from  what  is  known  as  “ bone  ” in  the  coal  which  is  supposed  to 
be  caused  by  a washing  in  of  sand  or  a mixture  of  sand  and 
clay  with  the  coal  at  the  time  of  its  deposition,  and  is  so  incor- 
porated with  the  coal  as  to  make  its  hand-sorting  impossible. 
Even  washing  and  concentrating  the  coal  slack  has  proved  at 
times  insufficient  to  separate  it.  This  sand  and  clay  is  of  course 
highly  siliceous  and  its  presence  in  a coke  makes  it  far  less  desira- 
ble to  the  smelters  than  a coke  with  a normal  or  self-fluxing  ash. 
An  example  may  make  this  clearer.  Taking  a normal  coke  with 
ash  at  nine  per  cent,  as  a standard  ; a coke  with  nineteen  pe*" 
cent,  ash  would  have  the  excess  of  ten  per  cent,  mainly  made  up 
of  sand  (or  silica)  and  clay  (or  silicate  of  alumina).  As  ore  of 
this  class,  which  it  replaces  in  the  furnace,  has  to  be  heavily 
fluxed  and  would  be  given  about  a fifteen  dollar  smelting  charge, 
we  can  readily  see  that  the  ten  per  cent,  excess  of  ash  would  cost 
the  lead-silver  smelters  of  this  State  about  one  dollar  and  a half 
per  ton  of  coke,  in  addition  to  the  fact  they  are  paying  for  ten 
per  cent,  of  dead  weight  instead  of  fuel.  The  furnaces  would 
also  work  poorly  with  such  a coke.  The  fine  broken  coke 
found  near  the  bottom  of  all  large  stock  piles  has  been  noticed  to 
run  especially  high  in  ash  and  silica.  Cases  have  come  under 
the  writer’s  observation  in  which  this  fine  material  forms  a very 
large  proportion  of  furnace  crust  or  barrings  and  one  case  in 
which  the  careless  use  of  too  much  fine  coke  directly  caused  the 
crusting  or  hanging.  The  high  ash  in  coke  may  also  be  largely 
due  to  the  presence  of  iron  oxide  from  the  burning  of  the  iron 
pyrites  present  in  the  coal.  This  helps  to  flux  the  silica  present 
and  is  to  that  extent  beneficial,  although  rarely  present  in  suffi- 
cient quantity  to  make  much  difference. 

I append  analyses  of  the  different  cokes  at  present  sold  in  the 


234 


GEO  LOG  y OF  COLORADO  COAL  LI  ELDS. 


State.  Through  the  kindness  of  my  friends  in  the  business, 
which  I acknowledge  more  properly  below,  I have  been  able  to 
obtain  the  smelter  average  of  the  different  cokes.  In  consequence 
the  analyses  give  the  average  of  an  aggregate  of  several  thous- 
and tons  ; the  figures  being  averages  of  analyses  of  samples  of 
as  high  as  fifteen  lots  of  two  or  three  hundred  tons  each.  Nearly 
forty  lots  and  over  sixty  analyses  are  represented  in  the  figures 
given,  which  have  been  condensed  in  order  to  give  the  informa- 
tion in  as  concise  a form  as  possible. 

We  shall  first  take  up  the  Trinidad  coking  coal  fields  as  being 
the  oldest  and  largest  producers.  In  El  Moro  coke  the  water  is 
invariably  low,  under  0.5  per  cent.  The  volatile  matter  is  also 
low,  averaging  under  1 per  cent.  The  fixed  carbon  runs  from 
76.6  per  cent,  to  80.3  per  cent,  with  an  average  of  79.1  per 
cent,  in  six  determinations.  The  ash  in  twelve  determinations  of 
coarse  coke  averaged  18.7  per  cent.,  the  highest  being  22.3  per 
cent.,  the  lowest  16.5  per  cent.  The  silica  in  the  ash  showed  an 
average  of  67  per  cent,  ranging  between  65.2  per  cent,  and  68.5 
per  cent.  The  iron  in  the  ash  showed  an  average  of  7.6  per 
cent,  varying  between  6 per  cent,  and  8.5  per  cent.  The  reducing 
power,  determined  by  Berthier’s  method,  gave  an  average  of 
24.12  grammes  of  lead  or  71  per  cent,  as  compared  with  pure 
carbon.  This  method  has  been  proved  by  investigation  to  give 
results  constantly  about  one-ninth  below  the  theoretical  reduc- 
ing power,  so  the  above  statement  may  be  accepted  as  conserva- 
tive. Some  analyses  of  the  remaining  constitutents  of  the  ash 
gave  21  per  cent,  of  alumina  and  1.5  per  cent,  of  lime.  This 
would  indicate  either  that  the  coal  had  not  been  thoroughly 
cleaned  from  slate,  or  that  clay,  as  well  as  sand,  was  a constituent 
of  the  “ bone.”  The  former  case  would  seem  more  probable. 
The  coke  from  Starkville  and  other  points  in  this  region  shows 
the  same  peculiarity,  high  and  siliceous  ash.  The  average  of  a 
large  number  of  lots,  of  which  the  writer  had  personal  knowledge, 
was  20.5  per  cent  ranging  between  17.5  per  cent,  and  24  per 
cent.  This  peculiarity  of  the  coking  coals  of  this  district  led  to 
an  attempt  to  free  the  slack  from  slate  and  “ bone  ” by  washing 
before  coking,  as  is  successfully  done  in  some  foreign  districts. 
The  effort  was  not  continued,  whether  because  too  costly  or 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


235 


because  the  impurity  was  too  thoroughly  incorporated  in  the 
coal  as  “ bone ; ” the  writer  has  heard  the  latter  cause  assigned. 
The  parts  of  coke  having  an  especially  high  ash  seem  most  fri- 
able, as  we  find  that  the  fine  or  broken  coke  has  a markedly 
higher  and  more  siliceous  ash.  An  analysis  of  a sample  of  fine 
El  Moro  coke  gave  26  per  cent,  ash  which  contained  70.33  per 
cent,  of  silica  and  5 per  cent,  of  iron. 

The  Trinidad  coals,  with  the  exception  of  the  high  ash,  which 
nearly  all  Rocky  Mountain  coking  coals  yet  discovered  show,  are 
good,  coking  readily  and  making  a strong,  coherent  product, 
which  finds  a good  market  in  Pueblo,  Denver,  Leadville  and 
elsewhere. 

We  shall  next  consider  the  Durango  coke,  necessarily  briefly, 
as  the  coke  is  only  locally  used  and  data  consequently  scant. 
The  San  Juan  smelter  gives  an  average  of  11  per  cent,  ash  for 
the  coke  from  the  Porter  mine,  and  13  per  cent,  ash  for 
that  of  the  San  Juan  mine.  As  these  figures  are  not  much  in 
excess  of  those  taken  as  normal  or  self-fluxing,  and  the  coal 
analyses  given  in  Prof.  Lake’s  report,  give  equally  good  results, 
we  may  safely  assume  that  distance  from  a larger  market  alone 
restricts  the  production. 

The  Crested  Butte  coke  shows  a large  variation  which,  how- 
ever, is,  to  some  extent,  regular  and  chronological.  A number 
of  data  show  that,  up  to  within  about  two  years,  the  ash  was 
extremely  low,  running  only  four  to  five  per  cent.,  and  of  course 
self  fluxing. 

About  the  winter  of  1887  and  1888  its  character  began  to 
change,  the  ash  becoming  higher,  until  at  present  it  ranges  in 
averages  from  8 per  cent,  to  13  per  cent.,  although  some 
grab  samples  went  as  high  as  17  per  cent.  A recent  average 
analysis  is  as  follows:  Water 0.32  per  cent.,  volatile  matter  0.49 
per  cent.,  fixed  carbon  87.02  per  cent,  ash  12.17  Per  cent.,  the 
reducing  power  76.65  per  cent.  The  ash  was  somewhat  siliceous, 
having  44.2  per  cent,  silica,  16.43  Per  cent,  iron,  the  remainder 
being  made  up  of  other  bases.  Samples  with  lower  ash  are  self- 
fluxing  or  basic.  This  coke  is  not  so  strongly  coherent  as  that 
from  Trinidad,  but  still  is  good.  It  is  largely  marketed  in  Gun- 
nison and  Utah  smelting  points. 


236 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


The  Grand  river  coking  coal  fields,  although  but  recently 
opened,  are  making  a strong  bid  for  public  favor.  Although  the 
writer  has  over  twenty  analyses  of  cokes  from  this  district,  most 
of  them  on  large  lots,  the  exact  locality  could  not  in  most  cases 
be  obtained.  The  first  lot  was  labelled  “ Colo.  Midland.”  In 
fifteen  analyses  the  water  was  mostly  under  i per  cent,  and  in 
one  case  only,  over  2 per  cent.  The  volatile  combustible  was 
always  under  two  per  cent,  and  in  most  cases  under  one  percent., 
the  fixed  carbon  ran  from  79.76  percent,  to  88.58  per  cent,  with 
an  average  of  83.78  per  cent.  The  ash  ran  from  10. 1 per  cent, 
to  19. 1 per  cent,  with  an  average  of  14  per  cent.  The  silica  in 
the  ash  ran  from  45  per  cent,  to  54  per  cent,  with  an  average  of 
50.6  per  cent.  The  iron  ran  from  7.33  per  cent,  to  14  95  per 
cent,  with  an  average  of  10.6  per  cent. 

A sample  of  fine  coke  showed  the  same  high  silica  in  the  ash 
as  mentioned  above,  the  amount  being  74  per  cent.,  which  is 
notably  higher  than  in  any  of  the  coarse  samples. 

The  average  reducing  power  of  these  cokes  as  compared  with 
carbon  was  75.75  per  cent. 

Another  batch  of  analyses  which  were  called  “ Grand  River 
coke  ” are  on  samples  taken  when  the  coke  was  suspected  of 
being  below  the  average  quality.  They  had  an  average  ash  of 
15  per  cent.,  ranging  between  13.4  per  cent,  and  16.8  per  cent. 

The  silica  in  the  ash  ran  from  50.3  per  cent,  to  60.4  per  cent, 
with  an  average  of  56.6  per  cent.  The  iron  varied  between  14.4 
per  cent,  and  16.5  per  cent.,  with  an  average  of  15.2  per  cent. 

An  average  lot  of  the  Marion  coke  gave  9.6  per  cent,  ash, 
which  contained  35.4  per.  cent  silica,  and  21.14  per  cent.  iron. 
This,  allowing  the  difference  to  other  bases  would  be  nearly  or 
quite  self-fluxing.  The  higher  amount  of  iron  in  the  Grand  river 
cokes  would  make  the  ash  more  nearly  self-fluxing  and  would 
also  indicate  the  probable  presence  of  some  residual  sulphur  from 
the  burning  of  the  iron  pyrites  in  the  coal.  Two  tests  for  this 
gave  respectively  1.35  per  cent,  and  0.947  per  cent,  sulphur. 

It  might  be  well  to  state,  for  purposes  of  comparison,  that 
Connelsville,  Pa.,  coke  runs  about  1 1 per  cent,  ash,  and  Alabama 
coke  13  per  cent.,  although  the  data  obtained  are  a little  scant. 
Many  English  and  foreign  cokes  run  as  low  as  5 per  cent,  ash, 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  237 

which  is  due  at  times  to  the  purity  of  coal  and  care  in  sorting 
out  slate  and  at  other  times  to  mechanical  preparation  and  the 
washing  of  the  slack.  While  the  high  price  of  labor  would  ren- 
der the  same  degree  of  preparation  unprofitable  in  this  country, 
still,  if  a suggestion  is  allowable,  it  would  be  to  exercise  the  maxi- 
mum degree  of  care  in  keeping  the  slaty  and  other  impurities 
out  of  the  coking  coal.  The  smelters  do  not  want  to  smelt  more 
clay  and  sand  gratis  than  they  have  to,  and  the  purest  product 
should  and  will  command  a premium. 

Itwould  be  ungrateful  in  the  writer  to  close  this  article  with- 
out acknowledging  his  indebtedness  to  the  following  gentlemen  : 
Messrs.  Edwin  N.  and  J.  Dawson  Hawkins,  chemists  of  the 
Globe  Smelter,  Denver;  Mr.  R.  C.  Canby,  Superintendent  of  the 
Arkansas  Valley  Smelter,  Leadville  ; Mr.  P.  S.  Morse,  Superin- 
tendent of  the  Germania  Smelter,  Salt  Lake,  Utah  ; Mr.  E.  J.  H. 
Amy,  Assistant  Manager,  San  Juan  Smelter,  Durango,  and 
others. 

Their  kindness  in  furnishing  data  has  enabled  him  to  give 
reliable  averages  from  large  lots,  instead  of  analyses  of  “ grab  ” 
samples  which  would  be  necessarily  inaccurate  and  often 
misleading. 


Appendix. 


Appendix. 

AGE  OF  THE  ARAPAHOE  AND  DENVER  BEDS 

AND  DISCOVERY  OF  A GIGANTIC  FOSSIL  “ HORNED  TOAD.” 

We  have  assumed  in  this  report  that  the  Denver  and  Arapahoe 
beds  of  the  Denver  basin  are  of  Tertiary  age  on  the  authority  of 
the  recent  reports  of  the  U.  S.  geological  survey,  but  not  because 
we  think  their  age  thereby  proved  beyond  a doubt.  It  is  still  a 
question  whether  they  are  not  after  all  upper  local  subdivisions 
of  the  Laramie  Cretaceous.  The  recent  discoveries  of  extra- 
ordinary Dinosaur  remains  in  these  beds  and  in  the  Laramie 
group  favor  the  latter  view,  otherwise  these  discoveries  would 
drive  us  to  the  conclusion  that  these  great  saurians  lived  on 
beyond  the  Cretaceous  into  the  Tertiary  period,  a point  which 
paleozoologists  would  be  slow  to  admit. 

Since  we  began  this  report  Prof.  Marsh’s  party  has  dis- 
covered some  remarkable  Dinosaur  remains  in  these  beds  and 
those  of  the  Laramie,  called  the  Ceratopsidoe,  or  horned-faced 
saurians.  So  numerous  are  these  remains  at  different  points  in 
the  Upper  Cretaceous  along  the  eastern  flank  of  the  Rocky 
Mountains  in  Montana,  Wyoming  and  Colorado  that  Professor 
Marsh  has  named  the  horizon  in  which  they  occur,  the  “Ceratops 
beds.”  He  says,  “The  beds  in  which  these  bones  are  common 
are  in  the  Upper  Cretaceous.  They  are  fresh-water  or  brackish 
deposits  which  form  part  of  the  so-called  Laramie  group,  but  are 
below  the  uppermost  beds  referred  to  that  group.  In  some  places 
they  rest  upon  marine  beds  which  contain  invertebrate  fossils, 
characteristic  of  the  Fox-Hills  deposits.  The  fossils  asso- 
ciated with  the  Ceratopsidoe  are  mainly  Dinosaurs,  representing 
two  or  three  orders  and  several  families.  Plesiosaurs,  crocodiles 
and  turtles  of  Cretaceous  types,  and  many  smaller  reptiles,  have 
left  their  remains  in  the  same  deposits.  Numerous  small  mammals 
also  of  ancient  types,  a few  birds  and  many  fishes  are  likewise 


242  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

entombed  in  this  formation.  Invertebrate  fossils  and  plants  are 
not  uncommon  in  the  same  horizon.” 

Some  remarkably  perfect  skulls  of  a species  of  these  gigantic 
Dinosaurs  called  Triceratops,  or  three-horned  faced  Dinosaur, 
were  recently  discovered  in  Wyoming  by  Mr.  T.  B.  Hatcher. 
Professor  Marsh  says,  “ that  the  skull  exceeds  in  size  that  of  any 
land  animal  extinct  or  living  and  is  only  surpassed  bv  that  of  the 
Cetaceans  or  whales.”  The  skull  is  over  eight  feet  in  length. 
The  mouth  was  armed  with  a sharp  cutting  beak  like  that  of  a 
snapping  turtle.  There  was  also  a strong  horn  on  the  bridge  of 
the  nose  and  a pair  of  very  large  pointed  horns  on  the  forehead, 
each  two  feet  six  inches  in  length.  (It  was  the  discovery  of 
fragments  of  these  horns  by  Messrs.  Eldridge  and  Cannon  in 
beds  in  the  Denver  basin,  supposed  to  be  of  Tertiary  age,  that 
led  them  at  first  to  be  considered  as  belonging  to  the  great  extinct 
buffalo — Bison  Alticornis).  As  if  such  extraordinary  armature 
was  not  sufficient,  there  was  a row  of  sharp  projections  around 
the  back  of  the  head,  like  a mastiff’s  spiked  collar.  “ For 
offense  or  defense  they  formed  together  an  armor  for  the  head 
as  complete  as  any  known.  This  armature  dominated  the  skull, 
and  in  a great  measure  determined  its  form  and  structure.”  The 
skull  itself  is  wedge-shaped  in  form,  being  very  broad  and  mas- 
sive toward  the  forehead  and  back,  to  support  the  heavy  arma- 
ture, and  tapering  toward  the  snout.  The  teeth  were  compar- 
atively small  and  crenated,  resembling  those  of  the  ancient 
Hadrosaurus  or  the  modern  Iguana,  and  show  by  their  structure 
that  the  animal  was  of  herbivorous  habits,  and  probably  inof- 
fensive, relying  upon  his  extraordinary  defensive  armature  for 
protection  against  the  onslaughts  of  the  terrible  carnivorous 
Dinosaurs. 

The  modern  living  creature  that  this  extraordinary  monster 
most  resembled  is  the  little  horned  lizard  (Phrynosoma),  com- 
monly called  a “ horned  toad,”  often  found  on  our  Colorado 
prairies.  The  size  of  the  monster  Prof.  Marsh  has  not  yet  told 
us,  but,  judging  from  its  enormous  head,  it  must  have  been  truly 
gigantic. 

If  we  can  picture  to  our  imagination  a “ horned  toad  ” of 
more  than  elephantine  proportions,  bristling  with  horns  and 


GEOLOGY  OF  COL  OF  A BO  COAL  FIELDS. 


243 


spikes,  with  a huge  head,  armed  on  the  forehead  with  two  long, 
sharp  horns,  greater  than  those  of  the  long-horned  rhinoceros, 
and  a smaller  horn  on  the  nose,  we  may  form  some  conception 
of  the  monster  that  roamed  among  the  palmettos  and  ferns  that 
clothed  the  marshes  of  our  coal  period  in  Colorado,  or  plunged 
into  the  lakes  around  which  that  beautiful  tropical  vegetation 
grew — vegetation  now  either  preserved  in  fossil  imprints  or 
turned  into  coal.  The  discovery  of  perfect  skulls  of  these  Din- 
osaurs in  Wyoming  throws  much  light  upon  the  few  scattered 
saurian  remains  that  have  been  found  from  time  to  time  in  the 
leaf  beds  of  the  Table  Mountains  at  Golden  and  similar  strata 
under  Denver.  Doubtless  these  bones  belong  to  the  same 
species,  or  to  genera  of  Dinosaurs  allied  to  them. 


COAL  PRODUCTION. 

[By  Hon.  John  McNeil,  State  Inspector  of  Coal  Mines.] 

The  following  is  a summary  of  the  coal  statistics  of  the 
State  for  a number  of  years : 


Years.  Tons. 

1873  69.977 

1874  87,372 

1875  98,838 

1876  117,666 

1877  160,000 

1 878  200,630 

1879  322,732 

1880  375,ooo 

1881  706,744 

1882  1,061,479 

1883  1,220,593 

1884  1,130,024 

1885  i,398,796 

1886  1,436,211 

1887  L791.735 

1888  ...  2,185,477 

1889  2,373.954 


244  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

Production  of  coal  for  year  1887,  by  counties,  is  as  follows 


Counties.  Tons. 

Las  Animas  (including  coal  made  into  coke)...  506,540 

Fremont 417,326 

Boulder 297,338 

Gunnison  (including  coal  made  into  coke) 243,122 

Huerfano  131,810 

Weid  39,281 

El  Paso 47,517 

Garfield  (including  coal  made  into  coke) 26,000 

Pitkin 4,000 

La  Plata  (including  coal  made  into  coke) 22,880 

Park 23,421 

Arapahoe  16,000 

J efferson 12 ,000 

Douglas. 3,5°° 

Dolores 1 ,000 


Total I.79I.735 


For  the  year  ending  December  31,  1888,  the  returns  of  the 
corl  production  made  to  this  office,  and  estimates  made  for  latter 
part  of  December,  are  2,185,477  tons,  of  2,000  pounds.  Of  the 
above  amount,  700,547  tons,  or  a little  over  32  per  cent,  of  the 
State’s  production,  have  been  shipped  outside  the  State  to  points 
in  Kansas,  Texas  and  Nebraska. 

Production  by  counties  is  as  follows : 


Las  Animas  (including  coal  for  coke) 706,455 

Fremont 438,789 

Boulder 3 1 5 » r 5 5 

Gunnison  (including  coal  for  coke) 258,374 

Huerfano 159,610 

Garfield 115,000 

La  Plata  (including  coal  for  coke) 33,625 

Pitkin  (including  coal  for  coke) 28,113 

Weld. 28,054 

El  Paso : 44,114 

Jefferson . . 9,000 

Arapahoe 1,700 

Park 46,588 

Douglas 400 

Mesa  300 

DQfores.,, 200 

Total 2,185,477 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


245 


Production  by  counties  for  the  year  ending  December,  21st, 
1889,  showing  increase  and  decrease  over  and  from  figures  of 
1888.  The  month  of  December  is  partly  estimated: 


Counties. 


Tons 

(2,000.) 


Incrse. 


Decr'se. 


Arapahoe 900 

Boulder > . 297,703 

Douglas 300 

Dolores.. none 

El  Paso 54,066 

Fremont 279,855 

Gunnison 251,808 

Garfield 144,627 

Huerfano 309,023 

Jefferson 6,600 

Las  Animas 876,990 

La  Plata 32,630 

Mesa none 

Park 47,005 

Pitkin 46,181 

Weld 26,176 


600 
17,362 
100 
200 

9.952 

'58,943 

6,566 

29,627 

1 49413 

2,400 

170,535 

995 

300 

4i7 

18,068 

1,878 


2,373.954 

Output  for  1888,  2,185,477;  Output  for  1889,  2,373,954, 
being  an  increase  over  1888  of  188,477  tons. 


The  average  value  of  coal  on  the  cars  at  the  mines  is  $2.20 
per  ton,  making  the  value  of  the  State’s  production  in  1888 
$4,808,049.40.  The  average  number  of  persons  employed  is  5,375. 
The  average  thickness  of  the  coal  seams  now  being  worked 
hrough  out  the  State  is  5 feet  5 inches  ; the  thickest  is  45  feet,  and 
the  thinnest,  1 foot  8 inches.  The  average  price  paid  to  miners 
for  digging  and  loading  the  coal  and  timbering  the  working 
places  is  70  1-5  cents  per  ton  of  2,000  pounds  of  screened  coal, 
average  screen  being  about  1 ^ inches  between  bars.  The 
average  cost  of  producing  the  coal  on  the  cars  at  the  mines, 
including  royalty,  is  about  $1.80. 


246 


GEOLOGY  OF  COL  OF  A BO  COAL  FIELDS. 


VARIETIES  OF  COAL 

AND  WHAT  QUALITIES  AND  PROPERTIES  DISTINGUISH  GOOD  COAL 
FROM  INFERIOR.  LE  CONTE’S  GEOLOGY. 

“Varieties  of  coal  depend  on  purity,  degree  of  bituminization, 
proportion  of  fixed  and  volatile  matter. 

Coal  consists  partly  of  organic  or  combustible,  and  partly  of 
inorganie  or  incombustible  matter. 

On  burning  coal  the  organic  combustible  matter  is  consumed 
and  passes  away  in  the  form  of  gas,  while  the  inorganic  incom- 
bustible is  left  as  ash.  The  relative  proportion  of  these  may  vary 
to  any  extent.  We  may  have  a coal  of  only  2 per  cent,  ash,  or  one 
of  5,  10,  15,  20  per  cent,  ash,  the  coal  is  now  becoming  poor.  A 
coal  of  30  or  40  per  cent,  ash  is  bony  or  shaly  coal  and  valueless. 
When  it  reaches  50  or  60  per  cent,  ash  it  is  merely  a coaly  shale 
from  which  it  passes  into  the  blackened  or  ordinary  shale  of  the 
roof  of  a coal  mine. 

All  vegetable  tissue  contains  incombustible  matter  which  is 
left  in  burning  as  ash.  The  amount  of  ash  in  vegetable  matter  is 
about  1 to  2 per  cent.  If  a coal  contains  5 per  cent,  or  less  of 
ash  it  is  considered  as  absolutely  pure,  i.  e.  its  ash  comes  wholly 
from  the  vegetable  tissues  of  which  it  is  formed,  but  if  a coal  con- 
tains 10  per  cent,  or  more  it  is  impure,  having  been  mixed  with 
mud  at  the  time  of  its  formation  and  accumulation. 

Vegetable  matter  accumulated  in  different  geological  periods, 
is  in  different  stages  of  that  peculiar  change  called  bituminization; 
brown  coal  and  lignite  are  examples  of  such  imperfect  coal  and 
are  comparatively  modern. 

Coal  even  when  pure  and  perfectly  bituminized  consists  of 
different  varieties  having  different  uses,  depending  upon  the  pro- 
portion of  fixed  and  volatile  matters. 

In  pure,  perfect  coal  the  combustible  matter  is  part  fixed,  part 
volatile.  These  may  be  separated  by  heating  to  a redness  in  a 
retort.  The  volatile  matter  is  thus  driven  off  and  may  be  col- 
lected as  oil  or  tar  in  condensers,  and  as  permanent  gas  in  gas- 
ometer s;  the  fixed  matter  is  left  in  the  retort  as  coke.  The  pro- 


GEOLOGY  OF  COLORADO  COAL  FIELDS.  247 

portion  of  these  varies  in  different  coals  and  affects  the  uses  to 
which  coal  is  applied.  If  the  coal  is  wholly  fixed  carbon  it 
is  graphite  or  black  lead  and  nearly  incombustible  ; not  used  as 
coal,  but  as  a lubricator  of  engines,  for  lead  pencils,  crucibles,  etc. 
It  is  coal,  but  the  last  term  of  the  coal  series. 

When  the  combustible  matter  contains  90  or  95  per  cent, 
fixed  carbon,  it  is  called  anthracite,  burning  with  no  flame  and 
producing  much  heat.  It  is  an  excellent  domestic  coal  and  with 
hot  blast  may  be  used  in  smelting  furnaces. 

If  the  combustible  matter  contains  80  to  85  per  cent,  fixed 
carbon  and  15  to  20  per  cent,  volatile  matter,  it  is  semi-anthracite 
or  semi-bituminous  coal.  This  is  free  burning,  producing  long 
flame  and  high  temperature,  and  does  not  coke  or  clog.  This  is 
especially  good  for  rapid  production  of  steam  for  locomotives. 
If  the  volatile  combustible  matter  rises  to  30  or  40  per  cent.,  it 
becomes  full  bituminous  coal,  burning  with  a strong,  bright 
flame,  after  coking  and  forming  clinkers.  This  is  one  of  the 
commonest  kinds  of  coal. 

If  the  volatile  matter  is  about  50  per  cent,  it  is  highly  bitu- 
minous, or  fat  fusing  coal,  adapted  to  the  manufacture  of  gas  and 
coke. 

In  a general  way  we  estimate  the  ordinary  quality  of  coal 
mainly  by  its  high  or  low  per  cent,  of  fixed  carbon  or  amount  of 
ash.” 

Some  other  properties  are  also  to  be  considered,  viz : 
Whether  the  coal  slacks  or  not  on  exposure  to  the  atmosphere. 
This  is  a cause  of  great  waste  in  the  coal  bin  and  in  slacking  in 
the  coal  yards,  and  is  more  characteristic  of  the  lignitic  coals  of 
our  northeastern  area,  owing  to  their  high  per  cent,  of  water  con- 
tained, than  of  the  majority  of  coals  from  the  west  of  Colorado. 
Another  quality  is  the  fracture  of  the  coal.  It  is  a good  point  for 
the  coal  to  break  in  large,  solid,  square  blocks.  Some  coal  when 
struck  with  a pick  or  hammer  flies  into  small  coal,  almost  as 
wasteful  as  the  slacking  coal.  Coal  in  Colorado  is  rarely  good 
till  a certain  depth  has  been  gained  below  the  surface. 

In  estimating  the  comparative  values  of  coals  from  analyses 
the  following  points  should  be  borne  in  mind.  The  sulphur  in 


248  GEOLOGY  OF  COLORADO  COAL  FIELDS. 

coals  used  for  gas  making  produces  certain  poisonous  and  inju- 
rious gases,  which  impair  the  quality  of  the  resultant  illuminating 
gas.  In  a coking  coal  the  quality  of  the  coke  will  be  impaired 
(see  chapter  on  coke).  The  water,  which  occurs  in  large  per- 
centage in  all  lignite  coals,  is  not  only  dead  weight,  but  directly 
lessens  the  heating  effect  of  the  volatile  combustible  matter  and 
fixed  carbon  present.  Care  should  be  taken  in  sampling  lump 
lignite  coals  to  determine  the  water  very  promptly  after  the 
lumps  are  broken  up  as  the  water  dries  out  of  the  coal  very 
quickly  when  powdered,  and  the  results  would  be  so  low  as  to 
unduly  favor  the  lignite.  Coal  slack  of  this  class  shows,  on 
account  of  this  cause,  a uniformly  lower  percentage  of  water  than 
the  lump  coal. 

The  ash  in  a coal  is  dead  weight,  and  in  coking  coals  has 
other  bad  effects  mentioned  under  that  head. 

The  valuable  constituents  of  all  coals  are  the  fixed  carbon 
and  volatile  combustible.  Bituminous  coals,  high  in  fixed  carbon, 
are  mostly  coking.  A general  rule  may  be  made  that  the  higher 
the  percentage  of  fixed  carbon  in  a coal  the  greater  the  propor- 
tion of  its  heating  effect  which  may  be  practically  utilized.  The 
volatile  combustible  matter  in  a coal,  when  high,  makes  a coal 
especially  valuable  for  gas  making  and  for  metallurgical  and  other 
operations  in  which  a long  flame  is  required,  as  for  example  ore 
roasting.  For  steam  making  and  ordinary  heating  purposes  a 
considerable  portion  of  the  volatile  combustible  is  wasted  in  a 
thick  black  smoke,  unless  smoke  consumers  are  practicable  and 
are  used. 

Through  the  kindness  of  the  Messrs.  Hawkins,  chemists,  of 
the  Globe  Smelting  Company  of  Denver,  we  are  enabled  to  give 
analyses  of  bulk  shipments  of  coal  from  a number  of  mines  in 
this  state  which  will  give  a very  fair  idea  of  the  average  grade 
coal  on  the  market.  They  were  received  too  late  for  publication 
under  their  appropriate  heads  in  the  earlier  pages  of  this  report. 
They  represent  averages  of  from  one  to  five  lots. 


GEOLOGY  OF  COLORADO  COAL  FIELDS. 


249 


Water. 

Volatile 

Matter. 

Fixed 

Carbon. 

Ash. 

Sulphur 

Cannon  Coal  Co.  (lump) 

17.84 

47.50 

29.84 

4.82 

“ “ (slack) 

I I.72 

42.68 

39-57 

6.02 

Louisville  (slack) 

12.70 

43-54 

36-30 

7 44 

Simpson  (lump) 

n-53 

43-19 

41-53 

3-74 

0.68 

“ (slack) 

7.88 

45-33 

40.81 

5.98 

Marshall  (lump) 

10.73 

44.11 

38.38 

6.77 

“ (slack) 

8.51 

45-41 

38.26 

£■32 

Fort  Worth  (slack) 

9.50 

50.22 

34-01 

6.27 

Colorado  Springs  (lump)  

18.04 

46.73 

30.79 

4.42 

C.  B.  & Q.  Coal  (lump) 

9.10 

45-99 

40.19 

4.69 

Rock  Springs  (lump) 

4.42 

4I.OI 

4997 

4-54 

Near  Rock  Springs  (lump) 

5.82 

27.50 

63.60 

3-07 

Como  (slack)  

2.65 

29.84 

41-79 

25.72 

C.  C.  & I.,  Trinidad  (lump) 

2.94 

3441 

46.01 

17  13 

Colorado  Fuel  Co.  (lump) 

2.05 

32.51 

52.90 

12.5 1 

1.27 

El  Moro(  lump) 

0.54 

30.29 

54  43 

H-74 

Baldwin  Coal  (lump) 

4-57 

44.15 

43-89 

7-39 

Cardiff  Coal  (lump) 

1.85 

37-79 

53-82 

6.54 

New  Castle  Coal  (lump) 

2.21 

36.18 

49  7 ‘ 

11. 14 

COKE  MANUFACTURED  DURING  1889. 


Counties. 

Tons 

(2,000  lbs) 

Incr'se. 

Decr’se. 

Gunnison 

2,158 

Las  Animas.. 

...119,436 

1,298 

Pitkin 

..  22,12*5 

6,125 

Garfield 

500 

500 

184,918 

*The  increase  and  decrease  of  the  coke  production  is  in 
comparing  1888  with  1889. 

*The  above  statistics  do  not  include  the  coke  produced  in 
the  Durango  district  (County  of  La  Plata).  The  Porter  and 
San  Juan  mines  in  this  district  produce  coke  enough  to  supply 
the  Durango  and  Rico  smelters,  in  all  three  stacks.  These,  at  a 
moderate  estimate,  would  consume  480  tons  of  coke  per  month, 
when  running  regularly.  We  may  safely  estimate  nine  months 
yearly  work  on  their  part,  which  would  make  a consumption  of 
4,320  tons  of  coke  yearly,  which  we  would  be  justified  in  adding 
to  the  above  report. 


. 


INDEX. 


INDEX. 


Air  Compressors 71 

Altered  Coal 105 

Amargo  1 1 8 

American  Bank  Note  Co 7 

Analysis,  49,  60,  71,  9 7,  101,  106,  109,  132,  133,  157,  160, 

165,  166,  169,  170,  185,  189,  190,  191,  192.  193,  194, 

I99>  230 

Animas  River 1 19 

Geology  of  122 

Anthracite 105,  184,  192,  203,  247 

Anthracite  Mesa  179,  185 

Anticlinals  138 

Antonito  Vocano 116 

Arapahoe  Group 35,  42,  55 

Areas  of  Coal : 

Colorado 26 

Dakota 27 

Montana 27 

New  Mexico...  27 

Texas 27 

Wyoming 27 

Archean 37,38,212,  219 

Arkansas  Canon  83 

Artesian  Wells 116 

Ash 19,  91,  231,  232,  234,  246 

Atlantosaurus 39 

Baculites 109 

Baldwin  Mines 200 

Basal  Sandstone  67,  98,  100,  104,  118,  205,  210 

Baxter  Creek 180 

Big  Thompson  Creek . 45 

Black  Canon,  geolgy  of 209 

Black  Diamond  Mine 13 1 

Bog  Iron  Ore ...... 187 


254 


INDEX. 


Bone  in  Coal 69,  233, 

Book  Cliffs 

Building  Sandstone... 

Calorific  Values 

Cambrian 21 1, 

Cannon,  George 

Canon  City  

Canon  City  Area 79,  80, 

Carbonero  Coal  Seam 119,  124, 

Carboniferous  Age  in  Colorado 23, 

Carboniferous  Oil  Horizon 

Carboniferous  Strata 104,  116,  21 1,  212,  220, 

Cardiff  Coal  

Cascade  Mountain  

Cause  of  Coking 

Chama  River 

Chauvenet,  Prof.  Regis 71, 

Chicorica  Mesa 

Chicosa  

City  Bank  Mine 

Classification  of  Coal 19, 

Clay,  Pottery 

Clear  Creek  

Coal : 

Alabama  - 

Area,  of  Colo. 


Ash  of 19,  91,  231,  232,  234, 

At  Depth 

Beds,  extent  of 23,  88, 

Breaker 

Coking 90,  94,  127,  183,  204,  206,  229, 

Constituents  of 230,  232,  246, 

Cutting  Machines  71,  92, 

Dakota  

Eastern  States 23, 

Definition  of 

Formation  of 14,  19,  20, 

Former  extent  of 89, 


235 

152 

38 

234 

212 

43 

80 

245 

133 

24 

83 

224 

161 

187 

230 

11 7 

101 

88 

100 

f\  20 

47 

56 

54 

236 

26 

246 

47 

89 

186 

247 

247 

95 

27 

25 

13 

22 1 

206 


INDEX. 


255 


Fracture  of. 

Horizontal 

Lands,  Price  of 

Locating  of  Mines 

Metamorphism  of 15, 

Montana 

Natural  History  of 

New  Mexico 

Non-Coking 

Origin  of 13, 

Production  of 92,  96,  99, 

Prospecting  for 27,  206, 

Structure  of 

Texas 

Utah 23, 

Variability  of 

Varieties  of 

Wyoming 

Coal  Basin  District 

Coal  Creek 65,  82,  197, 

Coal  Ridge  Mine 

Cockroach,  Fossil 

Coke  : 

Colorado 229, 

Connellsville 

Crested  Butte 

Durango 

El  Moro....i 

Grand  River 

Marion 

Midland 


Coke  Ovens 95,  96, 

Colorado  Coal  and  Iron  Co 81, 

Colorado  Cretaceous, 22,  37,  39, 

Colorado  Fuel  Co 169, 

Colorado  Springs  Coal  — 

Commercial  Value  of  Coke 232, 

Como 222, 


l9 

48 

92 

29 

105 

27 

13 

27 

82 

H 

106 

210 

108 

2 7 

27 

89 

246 

27 

167 

198 

158 

224 

232 

236 

235 

235 

234 

236 

236 

236 

231 

180 

225 

186 

244 

246 

226 


256 


INDEX. 


Concretions,  calcareous 

Conejos  Range 

Corals,  Carboniferous 

Cottonwood  Canon  

Crested  Butte 

Crested  Butte,  Coking  Coal 
Crested  Butte  Mountain.... 

Cretaceous 

Fosils  of 

Marine  Beds  of 

Cross,  Whitman  

Cuchara  River 

Curricanti  Needle  

Dakota,  Coal  of 

Dakota  Group 

Dakota  Sandstones 

Danforth 

Deer  Creek 

Definition  of  Coal  

Deinosaurs 

Deltas 

Denver  Basin  

Denver  Fuel  Co — 

Denver  Tertiary  Beds 

Dillon  Bed 

Districts  not  Reported 

Disturbed  Stratification 

Dolores  County 

Dotsero  Volcano 

Douglass,  Production 

Durango 

Geology  of 

Dykes 

East  River 

Eldredge,  George 

Elk  Mountains 

Elk  Mountain  Fuel  Co 

El  Moro  Mines 


107 

II7" 

42 

138,  144 

I73>  235.  244 

•••94,  183 

1 77 

22,  37,  39,  54,  2IO. 

- 163,  223 

i«5 

35,  43,  175 

102 

209 

27 

40,  54,  21 1 

75 

97 

45 

r3 

82,  240 

16 

35,  37,  45,  244 

95,  101 

35,  42 

89 

8 

16 

244 

145 

244 

115,  235,  244 

ii9 

101,  21 1,  225 

176 

• 35,45,  72 

173,  218 

148,  158 

9B  234 


INDEX. 

El  Paso  Co.,  Production 

Emmons,  S.  F.,  Geology  of  Rocky  Mts 

End  and  Face  Structure  19, 

Engleville 91, 

Erie 

Evanston  Rock  Spring 

Fairmount  Seam 

Faults 45,  173,  205,  220, 

Ferns 

Fire-brick,  Golden 

Fisher’s  Peak 90, 

Fissure  Veins 

Florence  Oil  Wells 39. 

Folds 138, 

Formation  of  Coal 14,  19,  20, 

Fossils,  40,  41,  57,  67,  83,  90,  100,  102,  109,  hi,  1 12,  152, 

163,  205,  223,  225, 

Fox-Hills  Group 22,  40,  41,  56,  81,  88,  109,  120,  210, 

Fracture  of  Coal 

Franceville 

Frying-Pan 

Fucoidal  Sandstone 67, 

Garfield  Co.,  Coal 

Coke 

Garo  Station 

Gases  in  Mines 


Gehrmann,  Chas.  A 184, 

General  Section 

Geology  of  Front  Range 218, 

Geology  of  Ore  Deposits 

Glacier... 21 1,  213, 

Glenwood 

Geology  of 

Hot  Springs 139, 

Gold  Belt  at  Ouray.  

Golden  Coal  Beds 53,  59, 

Golden  Fire-Brick 

Grand  Canon 


257 

244 

217 

89 

95 

46 

201 

129 

222 

57 

56 

91 

213 

80 

173 

221 

240 

225 

19 

80 

i37 

205 

244 

249 

223 

182 

189 

36 

220 

7 

226 

137 

141 

i43 

21 1 

244 

56 

83 


INDEX. 


258 

Grand  River  Coal.... 

Grand  River  Coal  Co 

Graphite 

Gray  Creek  Mines  ... 

Green  Mountain 

Greenhorn  Uplift 

Gunnison  Basin,  Geology  of 

Gunnison  County — 

Coke 

Gunnison  Mountains 

Gypsum  

Halymenites  

Harrison  Coal  Cutting  Machine 

Hayden  Survey 

Heat  at  Depth 

Hills,  R.  C 

Hogbacks 

Horned  Toad 

Horseshoe  Canon 

Huerfano  Butte  

Huerfano  Park  ......  ... 

Huronian 

Insects,  Fossil.. 

Iron  Ore 

Irwin 

Jerome  Park  Coal  Fields 

Jurassic  Beds 

Jurassic  Oils  in 

Kidney  Iron  Ore — 

Laccolites 

Lafayette  Mine  

Lake  Beds 

La  Plata  Mine 

La  Plata  Co.,  Production 

Laramie,  Fossils 

Laramie  Group 

Las  Animas 

Leaves,  Fossil 


236 

157,  161 

98 

9C  97.  99 

43.  44 

no 

US 

173.  209,  244 

249 

197 

225 

67,  205 

7h  95 

35.  112 

14 

159. 169 

35. 83, 1 19, 220 

242 

224 

hi 

218,  224 

212 

224 

95. 98. 187. 213 

188 

<39. 161 

37. 38, 54 

83 

95.  98 

■ 90,  no,  115,  225 

67,6  9,70,  71 

58,  90 

1 2 1 , 124,  133 

244 

152 

.21,  41,  88,  119,  155,  240 

244,  249 

112 


INDEX. 


259 


Lechner  Coal  Cutters 

Le  Conte’s  Geology 

Leg  Coal  Cutte 

Lennox  Seam  

Letter  of  Transmittal 

Lignite,  Term  Misapplied 

Limit  of  Coking  Coal 

Lincoln  Mountain 

Little  Thompson 

Locating  Coal  Mines 

Long  Wall  System  

Louisville  Coal  Basin 

Loveland  Mine 

McNeil,  John,  Inspector 

Maitland  Seam 

Manitou,  Geology  of .... 

Marble  Beds 

Marine  Shales 

Marion  Mine 

Marshall 

Marshes  

Maxwell  Grant  

Mear’s  Road 

Meeker 

Mesosoic  Era 

Metamorphism  of  Coal... 

Methods  of  Mining 

Microscopic  Structure  .. 

Midland  R.  R.  Co 

Mineral  Springs 

Monero 

Montana,  Coals  of 

Montezuma  Valley 

Monument  Creek  Beds  

Mosquito  Range,  Geology  of. 

Mount  Lincoln 

Muncie  Anthracite 

Natural  History  of  Coal 


92 

246 

71 

107 

5 


25,  230 

206,  224,  229 
220 


45 

29 

81,  123 

65,  66,  68,  244,  249 

60 

9,  226,  242,  243 

107 

• 79 

168 

76,  8i 5 

163,  165,  236 

22,  71,  75,  245,  249 


87,  89 

212 

201,  204 

218,  222 

15,  105,  203,  206 

8l,  91,  IOO 

18 

169 

83,  107,  122,  I39 

I 18 

27 

120,  I 2 I 

43*  79 

221 

- 220 

193 

13*  21 


26o 


INDEX. 


Newberry,  Prof.  J.  S 26, 

Newcastle  District  

New  Line  Mine 

New  Mexico,  Coal  of 

Niobrara  Group  

Northwestern  Colorado  Coal  Fields 

Oak  Creek  

O-be- Joyful  Creek  

Ohio  Creek 

Ohio  Creek  Anthracite  Co 

Oil,  Geological  Position  of 

Oil,  Jurassic  Horizon  of 

Oil,  Origin  of 

Oil  Wells .. 

Origin  of  Coal 

Origin  of  Oil..  

Ouray,  Geology  of 

Gold  Belt  of 

Hot  Springs  of 

Paleozoic  Era  

Park  Coal  Fields  

Parks,  Geology  of 

Partings,  Formation  of 

Peat  Beds 

Pennsylvania  Coals,  Comparison  .... 

Petroleum 

Pictou  Coal  Mines 

Pike’s  Peak 

Pillar  and  Stall  System 

Pinon  Company 

Pitkin  Co. 

Porter  Mine 

Poverty  Gulch  

Pray  Coal  Mine  

Preface  

Production  of  Coal 

Prospecting  for  Coal  

Quaternary 


20,  167,  169,  192,  197,  201 

148,  249 

184 

27 

55 

137,  202,  206 

- 81 

180 

176 

200 

39 

33 

39,  88 

80,  82 

14.  15.  16 

39.  83 

209,  231 

21  I 

212 

218,  222 

217,  244 

218,  220 

17 

l6 

23O 

39 

10 7.  244 

79 

184 

1 1 1 

244,  249 

121,  122,  132,  135 

186 

148 

7 

..  92,  96,  99,  100,  243,  244 

27 

37.  53 


1 


/ 


INDEX. 


261 


Lake  Beds  58 

Rallston  Coal  Seam 59 

Rallston  Creek 44 

Ratan  Coal  Fields  87,  91,  94 

Ratan  Mountains 87,  97 

Rico  Coal 244,  249 

Roaring  Fork 137,  244 

Rocks,  Volcanic 89 

Rock  Creek  District.. 167,  203,  204,  244 

Rock  Springs 201,  249 

Rocy  Mountains,  General  Structure  of 217 


69* 


184 

91 

244 

229 

225 


Rolls,  Cause  of 

Room  and  Pillar  System 

Rouse  Coal  Mine 101 

Sadtler,  Prof.  B 1 1 2, 

Salt 

Sandstone,  Building 38 

San  Juan  Coal  Mine 120,  124,  132,  235 

San  Luis  Park  1 16 

Santa  Fe  R.  R.  Co.... 81 

Scranton  Coal  Beds 42 

Semi-Anthracite 184 

Shells 22,  223,  225 

Shores  Mine 120,  121 

Sierra  Blanca 116 

Silurian  Fossils  33 

Silverton 122 

Simpson  Coal  Mine  70 

Slate  River  ' 176 

Sopris  Mine  96 

Sopris  Peak  144 

Southern  Colorado  Coal  Co 107,  11 1 

South  Park  219 

Southwestern  Colorado 1 1 5 

Southwestern  Coal  Fields  117 

Spanish  Peaks......... 93,  115 

Spring  Gulch  Mine  164 

L Springs,  Mineral 83,  107,  122,  139,  143,  212,  223,  225 


262 


INDEX. 


Origin  of 143 

Starkville  Mines  89,93,  94 

Stratification  55 

Structure  of  Coal  108 

Subsidence  16,  22 

Sulphur  Springs  ....107,  225 

Sunshine  District  161 

Synclinal  Fold 138 

Table  Mountains 43 

Fossils  57 

Tail-Rope  System  of  Haulage  102,  106 

Taylor  River. 176 

Telluride,  Carboniferous  Coal  at  24 

Teocalli  Mountain  176 

Tertiary 37,  42,  219 

Beds 35,  hi 

Beds,  Denver  35 

Coal,  Mode  of  Occurrence  230 

Fossils go,  hi 

Lake  Beds 90,  219,  220 

Texas,  Coal  of 27 

Thickness  of  Cretaceous  Coal  Measures 203 

Tilden,  Prof.  Geo.  C 231 

Toltec  Gorge  1 17 

Tremble  Springs 122 

Trias 37,  38 

Triceratops  Deinosaur 242 

Trinidad 87 

Coal 87,  234 

Coal  Fields 234,  244 

Coal  and  Coke  Co.  93 

Coal  Plateau 109 

Geology  of 109 

Trout  Creek,  fossils 223 

Uncompahgre  River 210 

Unconformity  of  Strata 54 

Underground  Haulage 91,96,  102 

Union  Coal  Co 200,  226 

h 

/ 


INDEX. 


263 


Uplifts 15 

Utah,  Coal  of 

Ute  Canon  

Ute  Reservation 

Van  Diest,  Prof.  P.  H 

Variability  of  Coal  Seams — 

Veins,  Fissure  . 

Ventilation  of  Coal  Mines 

Volcanic  Rocks 

Volcanoes : 

Antonito 

Dotsero 

Victor  Mine 

Walsenberg  District 

Weathering,  effect  of  on  Coal 

Weber  Grits 

Welch  Coal  Mine  

Weld  County,  Production  of  Coal... 

•Wheatstone  Mountain 

Wheeler  Great  Coal  Seam  

White  Ash,  Coal  Mine  

White  River  Coal  

White  River  Plateau,  Uplift  ..  ....  . 

Whiterock  Mountain 

Williams  Canon  

Wood,  Composition  of 

Formation  of  Coal  from - 

Wyoming  Coal  

Yampa  River,  Coal  Beds  

Zeolites  in  Basalt 


no,  204,  206,  210,  221,  222 
23 

79 

116 

88,  89,  117 

89,  205 

213 

92,  95,  96,  99,  106,  182 

...89,  94,  209,  21 1,  213,  222 

116 

145 

99 

101,  102,  245 

230 

224 

66,  70 

244 

176, 1 78 

149 

58 

201,  204 

204 

177 

79 

21 

20 

23,  27 

203 

56 


Index  to  Plates. 


Facing  Page 


Coal  Ridge  at  Newcastle,  View  and  Section 

Coal  Ridge,  Elk  Mt.  Fuel  Co.  Mine,  View  and  Section 

Coal  Ridge,  Elk  Mt.  Fuel  Co.  Tunnel,  Section  

Coal  Ridge,  Sulphur  Gulch,  Section 

Crested  Butte,  Panorama 

Denver  Basin.  Section  


154 

158 

158 

158 

177 

36 


264 


INDEX. 


Durango,  Panorama  and  Section Frontispiece 

Elk  Creek  Section 152 

Engleville  Coal  Mines,  View 94 

Golden,  View  and  Section 58 

Gray  Creek  County  Mines,  View 96 

La  Plata  Coal  Mine,  View Frontispiece 

Louisville  Basin,  Section 74 

Marion  Mine,  Grand  River  Coal  and  Coke  Co.,  View  ...  164 

Marshall  Coal  Mines,  View 74 

Newcastle  Region,  View  Looking  North 152 

Newcastle  Region,  View  Looking  South 152 

Rouse  Coal  Mine,  View 104 

Sopris  Mine,  View 96 

Sopris  Peak  and  Elk  Mts.,  View  (Spring  Gulch  Mine)  . . 162 

South  Boulder  Creek,  Section 74 

Spanish  Peaks  Region,  Map no 

Starkville,  View . . 94 

Sunshine  Coal  Mine,  View  and  Section 164 

Trinidad  Region,  Map 87 

Trinidad  Region,  Sections 88 

Victor  Mine,  View 69 


ERRATA. 


P’GK 

LINE 

FOR 

READ 

3 

I from  bottom 

| Laboratory  Instructor 

f Prof,  of  Analyt- 
\ ical  Chemistry 

19 

5 

Laminoes 

Laminae. 

26 

5 from  bottom 

Insert  quotation  marks 
after  “phosphorus.” 

37 

Plate  II 

Willow 

Arapahoe. 

58 

Plate  III 

Willow 

Arapahoe. 

59 

1 

Omit  “and.” 

67 

3 from  bottom 

Geoligists 

Geologists. 

89 

3 from  bottom 

Inductions 

Undulations. 

93 

3 

Mimes 

Mines. 

104 

16 

Outline 

Outlier. 

104 

Plate  V 

Dyke  Mountain 

Silver  Mountain. 

1 12 

Last  line 

“ we  have  ” 

Prof.Sadtler  has, etc 

1 16 

22 

Boundry 

Boundary. 

1 16 

29 

Stata 

Strata. 

1 17 

7 from  bottom 

Tilled 

Tilted. 

1 22 

9 

Later 

Latter. 

130 

23 

Granite 

Gravity. 

ho: 

1 

Stream 

Steam. 

147 

S3 

Continued 

Comminuted. 

167 

3 

One 

! Our. 

168 

4 from  bottom 

Verticle 

Vertical. 

177 

'9 

Prophyry 

Porphyry. 

183 

6 

Loose 

Lose. 

189 

7 

Hear 

Here. 

213 

1 1 

Blue 

Hue. 

223 

5 

Promintory 

Promontory. 

223 

13 

Dydes 

Dykes. 

223 

3i 

Inoceram 

Inocerami. 

UNIVERSITY  OF  ILLINOIS-URBANA 


